diff --git a/docs/generators/java.md b/docs/generators/java.md
index 3db0a9bf5ac..2c51f7dfe27 100644
--- a/docs/generators/java.md
+++ b/docs/generators/java.md
@@ -148,6 +148,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 ## LANGUAGE PRIMITIVES
 
 <ul class="column-ul">
+<li>BigDecimal</li>
 <li>Boolean</li>
 <li>Double</li>
 <li>Float</li>
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenComposedSchemas.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenComposedSchemas.java
index e53ecf8a4cd..e2fe8187004 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenComposedSchemas.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenComposedSchemas.java
@@ -47,6 +47,22 @@ public class CodegenComposedSchemas {
         return not;
     }
 
+    public void setAllOf(List<CodegenProperty> allOf) {
+        this.allOf = allOf;
+    }
+
+    public void setOneOf(List<CodegenProperty> oneOf) {
+        this.oneOf = oneOf;
+    }
+
+    public void setAnyOf(List<CodegenProperty> anyOf) {
+        this.anyOf = anyOf;
+    }
+
+    public void setNot(CodegenProperty not) {
+        this.not = not;
+    }
+
     public String toString() {
         final StringBuilder sb = new StringBuilder("CodegenComposedSchemas{");
         sb.append("oneOf=").append(oneOf);
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
index 6e4adf5809f..0e2f2b4bc7c 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
@@ -39,6 +39,7 @@ import org.slf4j.LoggerFactory;
 
 import java.io.File;
 import java.util.*;
+import java.util.function.Predicate;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -190,6 +191,8 @@ public class JavaClientCodegen extends AbstractJavaCodegen
         modelPackage = "org.openapitools.client.model";
         rootJavaEEPackage = MICROPROFILE_REST_CLIENT_DEFAULT_ROOT_PACKAGE;
 
+        languageSpecificPrimitives.add("BigDecimal");
+
         // cliOptions default redefinition need to be updated
         updateOption(CodegenConstants.INVOKER_PACKAGE, this.getInvokerPackage());
         updateOption(CodegenConstants.ARTIFACT_ID, this.getArtifactId());
@@ -1019,6 +1022,16 @@ public class JavaClientCodegen extends AbstractJavaCodegen
         return codegenModel;
     }
 
+    @Override
+    protected boolean needToImport(String type) {
+        // add import for BigDecimal explicitly since it is a primitive type
+        if("BigDecimal".equals(type)) {
+            return true;
+        }
+
+        return super.needToImport(type) && !type.contains(".");
+    }
+
     @Override
     public ModelsMap postProcessModelsEnum(ModelsMap objs) {
         objs = super.postProcessModelsEnum(objs);
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/anyof_model.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/anyof_model.mustache
index 1bbf0f0fc8d..333dfbd81cf 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/anyof_model.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/anyof_model.mustache
@@ -70,7 +70,7 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                 @Override
                 public {{classname}} read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
 
                     {{#useOneOfDiscriminatorLookup}}
                     {{#discriminator}}
@@ -80,7 +80,7 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                     switch (discriminatorValue) {
                     {{#mappedModels}}
                         case "{{{mappingName}}}":
-                            deserialized = adapter{{modelName}}.fromJsonTree(jsonObject);
+                            deserialized = adapter{{modelName}}.fromJsonTree(jsonElement);
                             new{{classname}}.setActualInstance(deserialized);
                             return new{{classname}};
                     {{/mappedModels}}
@@ -94,10 +94,10 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                     // deserialize {{{.}}}
                     try {
                         // validate the JSON object to see if any exception is thrown
-                        {{.}}.validateJsonObject(jsonObject);
+                        {{.}}.validateJsonElement(jsonElement);
                         log.log(Level.FINER, "Input data matches schema '{{{.}}}'");
                         {{classname}} ret = new {{classname}}();
-                        ret.setActualInstance(adapter{{.}}.fromJsonTree(jsonObject));
+                        ret.setActualInstance(adapter{{.}}.fromJsonTree(jsonElement));
                         return ret;
                     } catch (Exception e) {
                         // deserialization failed, continue
@@ -106,7 +106,7 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
 
                     {{/anyOf}}
 
-                    throw new IOException(String.format("Failed deserialization for {{classname}}: no class matched. JSON: %s", jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for {{classname}}: no class matched. JSON: %s", jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -190,18 +190,18 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
     {{/anyOf}}
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to {{classname}}
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to {{classname}}
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate anyOf schemas one by one
     int validCount = 0;
     {{#anyOf}}
     // validate the json string with {{{.}}}
     try {
-      {{{.}}}.validateJsonObject(jsonObj);
+      {{{.}}}.validateJsonElement(jsonElement);
       return; // return earlier as at least one schema is valid with respect to the Json object
       //validCount++;
     } catch (Exception e) {
@@ -209,7 +209,7 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
     }
     {{/anyOf}}
     if (validCount == 0) {
-      throw new IOException(String.format("The JSON string is invalid for {{classname}} with anyOf schemas: {{#anyOf}}{{{.}}}{{^-last}}, {{/-last}}{{/anyOf}}. JSON: %s", jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for {{classname}} with anyOf schemas: {{#anyOf}}{{{.}}}{{^-last}}, {{/-last}}{{/anyOf}}. JSON: %s", jsonElement.toString()));
     }
   }
 
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/oneof_model.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/oneof_model.mustache
index dfe8bf015e7..fc817fbbf0d 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/oneof_model.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/oneof_model.mustache
@@ -8,6 +8,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -27,6 +28,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import {{invokerPackage}}.JSON;
@@ -43,9 +45,18 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                 return null; // this class only serializes '{{classname}}' and its subtypes
             }
             final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+            {{#composedSchemas}}
             {{#oneOf}}
-            final TypeAdapter<{{.}}> adapter{{.}} = gson.getDelegateAdapter(this, TypeToken.get({{.}}.class));
+            {{^isArray}}
+            final TypeAdapter<{{{dataType}}}> adapter{{{dataType}}} = gson.getDelegateAdapter(this, TypeToken.get({{{dataType}}}.class));
+            {{/isArray}}
+            {{#isArray}}
+
+            final Type typeInstance = new TypeToken<List<{{complexType}}>>(){}.getType();
+            final TypeAdapter<{{{dataType}}}> adapter{{complexType}}List = (TypeAdapter<List<{{complexType}}>>) gson.getDelegateAdapter(this, TypeToken.get(typeInstance));
+            {{/isArray}}
             {{/oneOf}}
+            {{/composedSchemas}}
 
             return (TypeAdapter<T>) new TypeAdapter<{{classname}}>() {
                 @Override
@@ -55,25 +66,45 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                         return;
                     }
 
+                    {{#composedSchemas}}
                     {{#oneOf}}
-                    // check if the actual instance is of the type `{{.}}`
-                    if (value.getActualInstance() instanceof {{.}}) {
-                        JsonObject obj = adapter{{.}}.toJsonTree(({{.}})value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
+                    // check if the actual instance is of the type `{{{dataType}}}`
+                    if (value.getActualInstance() instanceof {{#isArray}}List<?>{{/isArray}}{{^isArray}}{{{dataType}}}{{/isArray}}) {
+                    {{#isPrimitiveType}}
+                      JsonPrimitive primitive = adapter{{{dataType}}}.toJsonTree(({{{dataType}}})value.getActualInstance()).getAsJsonPrimitive();
+                      elementAdapter.write(out, primitive);
+                      return;
+                    {{/isPrimitiveType}}
+                    {{#isArray}}
+                      List<?> list = (List<?>) value.getActualInstance();
+        	            if(list.get(0) instanceof {{complexType}}) {
+        		            JsonArray array = adapter{{{complexType}}}List.toJsonTree(({{{dataType}}})value.getActualInstance()).getAsJsonArray();
+                        elementAdapter.write(out, array);
                         return;
+        	            }
+                    {{/isArray}}
+                    {{^isArray}}
+                    {{^isPrimitiveType}}
+                      JsonElement element = adapter{{{dataType}}}.toJsonTree(({{{dataType}}})value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
+                    {{/isPrimitiveType}}
+                    {{/isArray}}
                     }
-
                     {{/oneOf}}
+                    {{/composedSchemas}}
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: {{#oneOf}}{{{.}}}{{^-last}}, {{/-last}}{{/oneOf}}");
                 }
 
                 @Override
                 public {{classname}} read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
 
                     {{#useOneOfDiscriminatorLookup}}
                     {{#discriminator}}
+                    JsonObject jsonObject = jsonElement.getAsJsonObject();
+
                     // use discriminator value for faster oneOf lookup
                     {{classname}} new{{classname}} = new {{classname}}();
                     if (jsonObject.get("{{{propertyBaseName}}}") == null) {
@@ -98,11 +129,58 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                     ArrayList<String> errorMessages = new ArrayList<>();
                     TypeAdapter actualAdapter = elementAdapter;
 
+                    {{#composedSchemas}}
                     {{#oneOf}}
+                    {{^hasVars}}
+                    // deserialize {{{dataType}}}
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                    {{#isPrimitiveType}}
+                      if(!jsonElement.getAsJsonPrimitive().is{{#isBoolean}}Boolean{{/isBoolean}}{{#isString}}String{{/isString}}{{^isString}}{{^isBoolean}}Number{{/isBoolean}}{{/isString}}()) {
+                        throw new IllegalArgumentException(String.format("Expected json element to be of type {{#isBoolean}}Boolean{{/isBoolean}}{{#isString}}String{{/isString}}{{^isString}}{{^isBoolean}}Number{{/isBoolean}}{{/isString}} in the JSON string but got `%s`", jsonElement.toString()));
+                      }
+                      actualAdapter = adapter{{{dataType}}};
+                    {{/isPrimitiveType}}
+                    {{^isPrimitiveType}}
+                    {{^isArray}}
+                      {{{dataType}}}.validateJsonElement(jsonElement);
+                      actualAdapter = adapter{{{dataType}}};
+                    {{/isArray}}
+                    {{/isPrimitiveType}}
+                    {{#isArray}}
+                      if (!jsonElement.isJsonArray()) {
+                        throw new IllegalArgumentException(String.format("Expected json element to be a array type in the JSON string but got `%s`", jsonElement.toString()));
+                      }
+
+                      JsonArray array = jsonElement.getAsJsonArray();
+                      // validate array items
+                      for(JsonElement element : array) {
+                      {{#items}}
+                      {{#isPrimitiveType}}
+                      if(!element.getAsJsonPrimitive().is{{#isBoolean}}Boolean{{/isBoolean}}{{#isString}}String{{/isString}}{{^isString}}{{^isBoolean}}Number{{/isBoolean}}{{/isString}}()) {
+                        throw new IllegalArgumentException(String.format("Expected array items to be of type {{#isBoolean}}Boolean{{/isBoolean}}{{#isString}}String{{/isString}}{{^isString}}{{^isBoolean}}Number{{/isBoolean}}{{/isString}} in the JSON string but got `%s`", jsonElement.toString()));
+                      }
+                      {{/isPrimitiveType}}
+                      {{^isPrimitiveType}}
+                        {{{dataType}}}.validateJsonElement(element);
+                      {{/isPrimitiveType}}
+                      {{/items}}
+                      }
+                      actualAdapter = adapter{{{complexType}}}List;
+                    {{/isArray}}
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema '{{{dataType}}}'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for {{{dataType}}} failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema '{{{dataType}}}'", e);
+                    }
+                    {{/hasVars}}
+                    {{#hasVars}}
                     // deserialize {{{.}}}
                     try {
                         // validate the JSON object to see if any exception is thrown
-                        {{.}}.validateJsonObject(jsonObject);
+                        {{.}}.validateJsonElement(jsonElement);
                         actualAdapter = adapter{{.}};
                         match++;
                         log.log(Level.FINER, "Input data matches schema '{{{.}}}'");
@@ -111,15 +189,17 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                         errorMessages.add(String.format("Deserialization for {{{.}}} failed with `%s`.", e.getMessage()));
                         log.log(Level.FINER, "Input data does not match schema '{{{.}}}'", e);
                     }
-
+                    {{/hasVars}}
                     {{/oneOf}}
+                    {{/composedSchemas}}
+
                     if (match == 1) {
                         {{classname}} ret = new {{classname}}();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for {{classname}}: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for {{classname}}: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -140,9 +220,11 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
 
     {{/oneOf}}
     static {
+        {{#composedSchemas}}
         {{#oneOf}}
-        schemas.put("{{{.}}}", {{{.}}}.class);
+        schemas.put("{{{dataType}}}", {{{baseType}}}.class);
         {{/oneOf}}
+        {{/composedSchemas}}
     }
 
     @Override
@@ -167,13 +249,24 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
         }
 
         {{/isNullable}}
+        {{#composedSchemas}}
         {{#oneOf}}
-        if (instance instanceof {{{.}}}) {
+        if (instance instanceof {{#isArray}}List<?>{{/isArray}}{{^isArray}}{{{dataType}}}{{/isArray}}) {
+        {{#isArray}}
+            List<?> list = (List<?>) instance;
+        	if(list.get(0) instanceof {{complexType}}) {
+        		super.setActualInstance(instance);
+        		return;
+        	}
+            {{/isArray}}
+            {{^isArray}}
             super.setActualInstance(instance);
             return;
+        {{/isArray}}
         }
 
         {{/oneOf}}
+        {{/composedSchemas}}
         throw new RuntimeException("Invalid instance type. Must be {{#oneOf}}{{{.}}}{{^-last}}, {{/-last}}{{/oneOf}}");
     }
 
@@ -188,42 +281,79 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
         return super.getActualInstance();
     }
 
+    {{#composedSchemas}}
     {{#oneOf}}
     /**
-     * Get the actual instance of `{{{.}}}`. If the actual instance is not `{{{.}}}`,
+     * Get the actual instance of `{{{dataType}}}`. If the actual instance is not `{{{dataType}}}`,
      * the ClassCastException will be thrown.
      *
-     * @return The actual instance of `{{{.}}}`
-     * @throws ClassCastException if the instance is not `{{{.}}}`
+     * @return The actual instance of `{{{dataType}}}`
+     * @throws ClassCastException if the instance is not `{{{dataType}}}`
      */
-    public {{{.}}} get{{{.}}}() throws ClassCastException {
-        return ({{{.}}})super.getActualInstance();
+    public {{{dataType}}} get{{#isArray}}{{complexType}}List{{/isArray}}{{^isArray}}{{{dataType}}}{{/isArray}}() throws ClassCastException {
+        return ({{{dataType}}})super.getActualInstance();
     }
-
     {{/oneOf}}
+    {{/composedSchemas}}
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to {{classname}}
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to {{classname}}
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
+    {{#composedSchemas}}
     {{#oneOf}}
-    // validate the json string with {{{.}}}
+    // validate the json string with {{{dataType}}}
     try {
-      {{{.}}}.validateJsonObject(jsonObj);
+    {{^hasVars}}
+    {{#isPrimitiveType}}
+      if(!jsonElement.getAsJsonPrimitive().is{{#isBoolean}}Boolean{{/isBoolean}}{{#isString}}String{{/isString}}{{^isString}}{{^isBoolean}}Number{{/isBoolean}}{{/isString}}()) {
+        throw new IllegalArgumentException(String.format("Expected json element to be of type {{#isBoolean}}Boolean{{/isBoolean}}{{#isString}}String{{/isString}}{{^isString}}{{^isBoolean}}Number{{/isBoolean}}{{/isString}} in the JSON string but got `%s`", jsonElement.toString()));
+      }
+    {{/isPrimitiveType}}
+    {{^isPrimitiveType}}
+    {{^isArray}}
+      {{{dataType}}}.validateJsonElement(jsonElement);
+    {{/isArray}}
+    {{/isPrimitiveType}}
+    {{#isArray}}
+      if (!jsonElement.isJsonArray()) {
+          throw new IllegalArgumentException(String.format("Expected json element to be a array type in the JSON string but got `%s`", jsonElement.toString()));
+      }
+      JsonArray array = jsonElement.getAsJsonArray();
+      // validate array items
+      for(JsonElement element : array) {
+        {{#items}}
+        {{#isPrimitiveType}}
+        if(!element.getAsJsonPrimitive().is{{#isBoolean}}Boolean{{/isBoolean}}{{#isString}}String{{/isString}}{{^isString}}{{^isBoolean}}Number{{/isBoolean}}{{/isString}}()) {
+          throw new IllegalArgumentException(String.format("Expected array items to be of type {{#isBoolean}}Boolean{{/isBoolean}}{{#isString}}String{{/isString}}{{^isString}}{{^isBoolean}}Number{{/isBoolean}}{{/isString}} in the JSON string but got `%s`", jsonElement.toString()));
+        }
+        {{/isPrimitiveType}}
+        {{^isPrimitiveType}}
+        {{{dataType}}}.validateJsonElement(element);
+        {{/isPrimitiveType}}
+        {{/items}}
+      }
+    {{/isArray}}
+    {{/hasVars}}
+    {{#hasVars}}
+      {{{.}}}.validateJsonElement(jsonElement);
+      validCount++;
+    {{/hasVars}}
       validCount++;
     } catch (Exception e) {
-      errorMessages.add(String.format("Deserialization for {{{.}}} failed with `%s`.", e.getMessage()));
+      errorMessages.add(String.format("Deserialization for {{{dataType}}} failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
     {{/oneOf}}
+    {{/composedSchemas}}
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for {{classname}} with oneOf schemas: {{#oneOf}}{{{.}}}{{^-last}}, {{/-last}}{{/oneOf}}. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for {{classname}} with oneOf schemas: {{#oneOf}}{{{.}}}{{^-last}}, {{/-last}}{{/oneOf}}. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/pojo.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/pojo.mustache
index 117f08da9b4..a42ad9f60ae 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/pojo.mustache
@@ -448,25 +448,25 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to {{classname}}
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to {{classname}}
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!{{classname}}.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!{{classname}}.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in {{{classname}}} is not found in the empty JSON string", {{classname}}.openapiRequiredFields.toString()));
         }
       }
       {{^hasChildren}}
       {{^isAdditionalPropertiesTrue}}
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!{{classname}}.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `{{classname}}` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `{{classname}}` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
       {{/isAdditionalPropertiesTrue}}
@@ -475,14 +475,17 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : {{classname}}.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
       {{/-first}}
       {{/requiredVars}}
       {{/hasChildren}}
       {{^discriminator}}
+      {{#hasVars}}
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
+      {{/hasVars}}
       {{#vars}}
       {{#isArray}}
       {{#items.isModel}}
@@ -495,7 +498,7 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
       JsonArray jsonArray{{name}} = jsonObj.getAsJsonArray("{{{baseName}}}");
       // validate the required field `{{{baseName}}}` (array)
       for (int i = 0; i < jsonArray{{name}}.size(); i++) {
-        {{{items.dataType}}}.validateJsonObject(jsonArray{{name}}.get(i).getAsJsonObject());
+        {{{items.dataType}}}.validateJsonElement(jsonArray{{name}}.get(i));
       };
       {{/required}}
       {{^required}}
@@ -509,7 +512,7 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
 
           // validate the optional field `{{{baseName}}}` (array)
           for (int i = 0; i < jsonArray{{name}}.size(); i++) {
-            {{{items.dataType}}}.validateJsonObject(jsonArray{{name}}.get(i).getAsJsonObject());
+            {{{items.dataType}}}.validateJsonElement(jsonArray{{name}}.get(i));
           };
         }
       }
@@ -541,12 +544,12 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
       {{#isModel}}
       {{#required}}
       // validate the required field `{{{baseName}}}`
-      {{{dataType}}}.validateJsonObject(jsonObj.getAsJsonObject("{{{baseName}}}"));
+      {{{dataType}}}.validateJsonElement(jsonObj.get("{{{baseName}}}"));
       {{/required}}
       {{^required}}
       // validate the optional field `{{{baseName}}}`
       if (jsonObj.get("{{{baseName}}}") != null && !jsonObj.get("{{{baseName}}}").isJsonNull()) {
-        {{{dataType}}}.validateJsonObject(jsonObj.getAsJsonObject("{{{baseName}}}"));
+        {{{dataType}}}.validateJsonElement(jsonObj.get("{{{baseName}}}"));
       }
       {{/required}}
       {{/isModel}}
@@ -556,11 +559,11 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
       {{#hasChildren}}
       {{#discriminator}}
 
-      String discriminatorValue = jsonObj.get("{{{propertyBaseName}}}").getAsString();
+      String discriminatorValue = jsonElement.getAsJsonObject().get("{{{propertyBaseName}}}").getAsString();
       switch (discriminatorValue) {
       {{#mappedModels}}
         case "{{mappingName}}":
-          {{modelName}}.validateJsonObject(jsonObj);
+          {{modelName}}.validateJsonElement(jsonElement);
           break;
       {{/mappedModels}}
         default:
@@ -610,9 +613,10 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
 
            @Override
            public {{classname}} read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
              {{#isAdditionalPropertiesTrue}}
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              {{classname}} instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
@@ -636,7 +640,7 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
              return instance;
              {{/isAdditionalPropertiesTrue}}
              {{^isAdditionalPropertiesTrue}}
-             return thisAdapter.fromJsonTree(jsonObj);
+             return thisAdapter.fromJsonTree(jsonElement);
              {{/isAdditionalPropertiesTrue}}
            }
 
diff --git a/modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml b/modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml
index 0008870a205..0b1b7f8fff6 100644
--- a/modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml
+++ b/modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml
@@ -1109,6 +1109,22 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/ArrayOfEnums'
+  /values:
+    get:
+      tags:
+        - values
+      summary: Get some primitive variable values
+      description: ''
+      operationId: getSomeValues
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Variable'
+        '400':
+          description: Invalid Value
 servers:
   - url: 'http://{server}.swagger.io:{port}/v2'
     description: petstore server
@@ -2224,3 +2240,31 @@ components:
           items:
             type: string
           type: array
+    Variable:
+      description: Value object
+      properties:
+        name:
+          type: string
+          example: 'variable_1'
+        value:
+          $ref: '#/components/schemas/Value'
+      required:
+        - name
+        - value
+    Value:
+      oneOf:
+        - $ref: '#/components/schemas/Scalar'
+        - $ref: '#/components/schemas/Array'
+    Scalar:
+      description: Values of scalar type
+      oneOf:
+        - type: string
+          maxLength: 1089
+        - type: number
+        - type: boolean
+    Array:
+      description: Values of array type
+      type: array
+      minItems: 1
+      items:
+        $ref: '#/components/schemas/Scalar'
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Bird.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Bird.java
index a82e2f41f24..d57f30a4ea3 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Bird.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Bird.java
@@ -160,25 +160,26 @@ public class Bird {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Bird
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Bird
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Bird.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Bird.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Bird is not found in the empty JSON string", Bird.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Bird.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Bird` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Bird` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("size") != null && !jsonObj.get("size").isJsonNull()) && !jsonObj.get("size").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `size` to be a primitive type in the JSON string but got `%s`", jsonObj.get("size").toString()));
       }
@@ -207,9 +208,9 @@ public class Bird {
 
            @Override
            public Bird read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Category.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Category.java
index 58e377cc406..ec76051b063 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Category.java
@@ -160,25 +160,26 @@ public class Category {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Category.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Category` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Category` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -204,9 +205,9 @@ public class Category {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/DataQuery.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/DataQuery.java
index acc697cb904..65f02cee3b1 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/DataQuery.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/DataQuery.java
@@ -196,25 +196,26 @@ public class DataQuery extends Query {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to DataQuery
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to DataQuery
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!DataQuery.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!DataQuery.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in DataQuery is not found in the empty JSON string", DataQuery.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!DataQuery.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `DataQuery` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `DataQuery` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("suffix") != null && !jsonObj.get("suffix").isJsonNull()) && !jsonObj.get("suffix").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `suffix` to be a primitive type in the JSON string but got `%s`", jsonObj.get("suffix").toString()));
       }
@@ -243,9 +244,9 @@ public class DataQuery extends Query {
 
            @Override
            public DataQuery read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/DefaultValue.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/DefaultValue.java
index dff9b07ffb2..8de8e55d001 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/DefaultValue.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/DefaultValue.java
@@ -448,25 +448,26 @@ public class DefaultValue {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to DefaultValue
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to DefaultValue
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!DefaultValue.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!DefaultValue.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in DefaultValue is not found in the empty JSON string", DefaultValue.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!DefaultValue.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `DefaultValue` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `DefaultValue` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("array_string_enum_ref_default") != null && !jsonObj.get("array_string_enum_ref_default").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `array_string_enum_ref_default` to be an array in the JSON string but got `%s`", jsonObj.get("array_string_enum_ref_default").toString()));
@@ -520,9 +521,9 @@ public class DefaultValue {
 
            @Override
            public DefaultValue read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/NumberPropertiesOnly.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/NumberPropertiesOnly.java
index 96eca50f8e8..7a346582ee7 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/NumberPropertiesOnly.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/NumberPropertiesOnly.java
@@ -191,25 +191,26 @@ public class NumberPropertiesOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to NumberPropertiesOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to NumberPropertiesOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!NumberPropertiesOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!NumberPropertiesOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in NumberPropertiesOnly is not found in the empty JSON string", NumberPropertiesOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!NumberPropertiesOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `NumberPropertiesOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `NumberPropertiesOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -232,9 +233,9 @@ public class NumberPropertiesOnly {
 
            @Override
            public NumberPropertiesOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pet.java
index 0944584ff25..c24315dbc3f 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pet.java
@@ -343,38 +343,39 @@ public class Pet {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Pet.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Pet` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Pet` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       // ensure the required json array is present
       if (jsonObj.get("photoUrls") == null) {
@@ -392,7 +393,7 @@ public class Pet {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -421,9 +422,9 @@ public class Pet {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Query.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Query.java
index e802c8b7fdd..097316adcf4 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Query.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Query.java
@@ -219,17 +219,18 @@ public class Query {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Query
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Query
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Query.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Query.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Query is not found in the empty JSON string", Query.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("outcomes") != null && !jsonObj.get("outcomes").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `outcomes` to be an array in the JSON string but got `%s`", jsonObj.get("outcomes").toString()));
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Tag.java
index 3ac9a7272de..399769cb396 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/Tag.java
@@ -160,25 +160,26 @@ public class Tag {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Tag.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Tag` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Tag` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -204,9 +205,9 @@ public class Tag {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.java
index 649d7a2cccf..91003749d8f 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.java
@@ -216,25 +216,26 @@ public class TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter is not found in the empty JSON string", TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("size") != null && !jsonObj.get("size").isJsonNull()) && !jsonObj.get("size").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `size` to be a primitive type in the JSON string but got `%s`", jsonObj.get("size").toString()));
       }
@@ -266,9 +267,9 @@ public class TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter
 
            @Override
            public TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.java b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.java
index 156118d002e..8bd134c79ee 100644
--- a/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.java
+++ b/samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/model/TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.java
@@ -142,25 +142,26 @@ public class TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter is not found in the empty JSON string", TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("values") != null && !jsonObj.get("values").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `values` to be an array in the JSON string but got `%s`", jsonObj.get("values").toString()));
@@ -187,9 +188,9 @@ public class TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter {
 
            @Override
            public TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/model/SomeObj.java b/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/model/SomeObj.java
index badbbc828d1..d52b087d3e9 100644
--- a/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/model/SomeObj.java
+++ b/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/model/SomeObj.java
@@ -289,25 +289,26 @@ public class SomeObj {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to SomeObj
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to SomeObj
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!SomeObj.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!SomeObj.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in SomeObj is not found in the empty JSON string", SomeObj.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!SomeObj.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `SomeObj` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `SomeObj` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("$_type") != null && !jsonObj.get("$_type").isJsonNull()) && !jsonObj.get("$_type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `$_type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("$_type").toString()));
       }
@@ -339,9 +340,9 @@ public class SomeObj {
 
            @Override
            public SomeObj read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/apache-httpclient/docs/FakeApi.md b/samples/client/petstore/java/apache-httpclient/docs/FakeApi.md
index 6eb12aee357..68b521a0cfe 100644
--- a/samples/client/petstore/java/apache-httpclient/docs/FakeApi.md
+++ b/samples/client/petstore/java/apache-httpclient/docs/FakeApi.md
@@ -396,7 +396,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/apache-httpclient/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java b/samples/client/petstore/java/apache-httpclient/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
index 1b9d42f423a..45bbe45dbe5 100644
--- a/samples/client/petstore/java/apache-httpclient/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/apache-httpclient/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
@@ -148,15 +148,13 @@ public class ArrayOfArrayOfNumberOnly {
     // add `ArrayArrayNumber` to the URL query string
     if (getArrayArrayNumber() != null) {
       for (int i = 0; i < getArrayArrayNumber().size(); i++) {
-        if (getArrayArrayNumber().get(i) != null) {
-          try {
-            joiner.add(String.format("%sArrayArrayNumber%s%s=%s", prefix, suffix,
-                "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
-                URLEncoder.encode(String.valueOf(getArrayArrayNumber().get(i)), "UTF-8").replaceAll("\\+", "%20")));
-          } catch (UnsupportedEncodingException e) {
-            // Should never happen, UTF-8 is always supported
-            throw new RuntimeException(e);
-          }
+        try {
+          joiner.add(String.format("%sArrayArrayNumber%s%s=%s", prefix, suffix,
+              "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
+              URLEncoder.encode(String.valueOf(getArrayArrayNumber().get(i)), "UTF-8").replaceAll("\\+", "%20")));
+        } catch (UnsupportedEncodingException e) {
+          // Should never happen, UTF-8 is always supported
+          throw new RuntimeException(e);
         }
       }
     }
diff --git a/samples/client/petstore/java/apache-httpclient/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/apache-httpclient/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index 2cea68ab8b4..2e3e4c1d458 100644
--- a/samples/client/petstore/java/apache-httpclient/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/apache-httpclient/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -148,15 +148,13 @@ public class ArrayOfNumberOnly {
     // add `ArrayNumber` to the URL query string
     if (getArrayNumber() != null) {
       for (int i = 0; i < getArrayNumber().size(); i++) {
-        if (getArrayNumber().get(i) != null) {
-          try {
-            joiner.add(String.format("%sArrayNumber%s%s=%s", prefix, suffix,
-                "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
-                URLEncoder.encode(String.valueOf(getArrayNumber().get(i)), "UTF-8").replaceAll("\\+", "%20")));
-          } catch (UnsupportedEncodingException e) {
-            // Should never happen, UTF-8 is always supported
-            throw new RuntimeException(e);
-          }
+        try {
+          joiner.add(String.format("%sArrayNumber%s%s=%s", prefix, suffix,
+              "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
+              URLEncoder.encode(String.valueOf(getArrayNumber().get(i)), "UTF-8").replaceAll("\\+", "%20")));
+        } catch (UnsupportedEncodingException e) {
+          // Should never happen, UTF-8 is always supported
+          throw new RuntimeException(e);
         }
       }
     }
diff --git a/samples/client/petstore/java/google-api-client/docs/FakeApi.md b/samples/client/petstore/java/google-api-client/docs/FakeApi.md
index 627366e41db..829724b750d 100644
--- a/samples/client/petstore/java/google-api-client/docs/FakeApi.md
+++ b/samples/client/petstore/java/google-api-client/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/jersey1/docs/FakeApi.md b/samples/client/petstore/java/jersey1/docs/FakeApi.md
index 627366e41db..829724b750d 100644
--- a/samples/client/petstore/java/jersey1/docs/FakeApi.md
+++ b/samples/client/petstore/java/jersey1/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/jersey2-java8-localdatetime/docs/FakeApi.md b/samples/client/petstore/java/jersey2-java8-localdatetime/docs/FakeApi.md
index d21432dbf3e..277a09f049f 100644
--- a/samples/client/petstore/java/jersey2-java8-localdatetime/docs/FakeApi.md
+++ b/samples/client/petstore/java/jersey2-java8-localdatetime/docs/FakeApi.md
@@ -264,7 +264,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/jersey2-java8/docs/FakeApi.md b/samples/client/petstore/java/jersey2-java8/docs/FakeApi.md
index 84167f65462..3d7d6254677 100644
--- a/samples/client/petstore/java/jersey2-java8/docs/FakeApi.md
+++ b/samples/client/petstore/java/jersey2-java8/docs/FakeApi.md
@@ -264,7 +264,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/jersey3/docs/FakeApi.md b/samples/client/petstore/java/jersey3/docs/FakeApi.md
index 0663bb791e4..2fa172a50ba 100644
--- a/samples/client/petstore/java/jersey3/docs/FakeApi.md
+++ b/samples/client/petstore/java/jersey3/docs/FakeApi.md
@@ -260,7 +260,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/native-async/docs/FakeApi.md b/samples/client/petstore/java/native-async/docs/FakeApi.md
index eabbd418b17..eea0ccef720 100644
--- a/samples/client/petstore/java/native-async/docs/FakeApi.md
+++ b/samples/client/petstore/java/native-async/docs/FakeApi.md
@@ -640,7 +640,7 @@ public class Example {
 
 ### Return type
 
-CompletableFuture<[**BigDecimal**](BigDecimal.md)>
+CompletableFuture<**BigDecimal**>
 
 
 ### Authorization
@@ -716,7 +716,7 @@ public class Example {
 
 ### Return type
 
-CompletableFuture<ApiResponse<[**BigDecimal**](BigDecimal.md)>>
+CompletableFuture<ApiResponse<**BigDecimal**>>
 
 
 ### Authorization
diff --git a/samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java b/samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
index 856d6942ae8..e7ae0bcade9 100644
--- a/samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
@@ -153,11 +153,9 @@ public class ArrayOfArrayOfNumberOnly {
     // add `ArrayArrayNumber` to the URL query string
     if (getArrayArrayNumber() != null) {
       for (int i = 0; i < getArrayArrayNumber().size(); i++) {
-        if (getArrayArrayNumber().get(i) != null) {
-          joiner.add(String.format("%sArrayArrayNumber%s%s=%s", prefix, suffix,
-              "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
-              URLEncoder.encode(String.valueOf(getArrayArrayNumber().get(i)), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
-        }
+        joiner.add(String.format("%sArrayArrayNumber%s%s=%s", prefix, suffix,
+            "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
+            URLEncoder.encode(String.valueOf(getArrayArrayNumber().get(i)), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
       }
     }
 
diff --git a/samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index 6986ea26644..7b20ae0d924 100644
--- a/samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -153,11 +153,9 @@ public class ArrayOfNumberOnly {
     // add `ArrayNumber` to the URL query string
     if (getArrayNumber() != null) {
       for (int i = 0; i < getArrayNumber().size(); i++) {
-        if (getArrayNumber().get(i) != null) {
-          joiner.add(String.format("%sArrayNumber%s%s=%s", prefix, suffix,
-              "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
-              URLEncoder.encode(String.valueOf(getArrayNumber().get(i)), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
-        }
+        joiner.add(String.format("%sArrayNumber%s%s=%s", prefix, suffix,
+            "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
+            URLEncoder.encode(String.valueOf(getArrayNumber().get(i)), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
       }
     }
 
diff --git a/samples/client/petstore/java/native/docs/FakeApi.md b/samples/client/petstore/java/native/docs/FakeApi.md
index e8911736308..91d80311ed4 100644
--- a/samples/client/petstore/java/native/docs/FakeApi.md
+++ b/samples/client/petstore/java/native/docs/FakeApi.md
@@ -603,7 +603,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 
 ### Authorization
@@ -671,7 +671,7 @@ public class Example {
 
 ### Return type
 
-ApiResponse<[**BigDecimal**](BigDecimal.md)>
+ApiResponse<**BigDecimal**>
 
 
 ### Authorization
diff --git a/samples/client/petstore/java/native/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java b/samples/client/petstore/java/native/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
index 856d6942ae8..e7ae0bcade9 100644
--- a/samples/client/petstore/java/native/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/native/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
@@ -153,11 +153,9 @@ public class ArrayOfArrayOfNumberOnly {
     // add `ArrayArrayNumber` to the URL query string
     if (getArrayArrayNumber() != null) {
       for (int i = 0; i < getArrayArrayNumber().size(); i++) {
-        if (getArrayArrayNumber().get(i) != null) {
-          joiner.add(String.format("%sArrayArrayNumber%s%s=%s", prefix, suffix,
-              "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
-              URLEncoder.encode(String.valueOf(getArrayArrayNumber().get(i)), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
-        }
+        joiner.add(String.format("%sArrayArrayNumber%s%s=%s", prefix, suffix,
+            "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
+            URLEncoder.encode(String.valueOf(getArrayArrayNumber().get(i)), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
       }
     }
 
diff --git a/samples/client/petstore/java/native/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/native/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index 6986ea26644..7b20ae0d924 100644
--- a/samples/client/petstore/java/native/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/native/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -153,11 +153,9 @@ public class ArrayOfNumberOnly {
     // add `ArrayNumber` to the URL query string
     if (getArrayNumber() != null) {
       for (int i = 0; i < getArrayNumber().size(); i++) {
-        if (getArrayNumber().get(i) != null) {
-          joiner.add(String.format("%sArrayNumber%s%s=%s", prefix, suffix,
-              "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
-              URLEncoder.encode(String.valueOf(getArrayNumber().get(i)), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
-        }
+        joiner.add(String.format("%sArrayNumber%s%s=%s", prefix, suffix,
+            "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix),
+            URLEncoder.encode(String.valueOf(getArrayNumber().get(i)), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
       }
     }
 
diff --git a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Category.java b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Category.java
index 3ecdbda0716..5aef445f0cf 100644
--- a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Category.java
@@ -206,17 +206,18 @@ public class Category {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -259,8 +260,9 @@ public class Category {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Category instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/ModelApiResponse.java b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/ModelApiResponse.java
index 135ecf70fc0..f4f09dbfb17 100644
--- a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/ModelApiResponse.java
+++ b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/ModelApiResponse.java
@@ -234,17 +234,18 @@ public class ModelApiResponse {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelApiResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelApiResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelApiResponse is not found in the empty JSON string", ModelApiResponse.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -290,8 +291,9 @@ public class ModelApiResponse {
 
            @Override
            public ModelApiResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelApiResponse instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Order.java b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Order.java
index f5abae46523..004059b8f76 100644
--- a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Order.java
+++ b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Order.java
@@ -368,17 +368,18 @@ public class Order {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Order
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Order
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Order is not found in the empty JSON string", Order.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
       }
@@ -421,8 +422,9 @@ public class Order {
 
            @Override
            public Order read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Order instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Pet.java
index 39ba8d3643f..54d44c9c469 100644
--- a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Pet.java
@@ -394,27 +394,28 @@ public class Pet {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -435,7 +436,7 @@ public class Pet {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -481,8 +482,9 @@ public class Pet {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Pet instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Tag.java
index 9c1f9247b1b..97fe598e2e1 100644
--- a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/Tag.java
@@ -206,17 +206,18 @@ public class Tag {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -259,8 +260,9 @@ public class Tag {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Tag instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/User.java b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/User.java
index 2008add2959..f7aa406f479 100644
--- a/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/User.java
+++ b/samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/model/User.java
@@ -374,17 +374,18 @@ public class User {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to User
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to User
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in User is not found in the empty JSON string", User.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("username") != null && !jsonObj.get("username").isJsonNull()) && !jsonObj.get("username").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `username` to be a primitive type in the JSON string but got `%s`", jsonObj.get("username").toString()));
       }
@@ -442,8 +443,9 @@ public class User {
 
            @Override
            public User read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              User instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/docs/FakeApi.md b/samples/client/petstore/java/okhttp-gson-dynamicOperations/docs/FakeApi.md
index 98f0b0098b8..0736ffc044d 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/docs/FakeApi.md
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/docs/FakeApi.md
@@ -251,7 +251,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java
index 62ee8304532..38302f996d3 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java
@@ -132,25 +132,26 @@ public class AdditionalPropertiesAnyType {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesAnyType
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesAnyType
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesAnyType.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesAnyType.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesAnyType is not found in the empty JSON string", AdditionalPropertiesAnyType.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesAnyType.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesAnyType` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesAnyType` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -176,9 +177,9 @@ public class AdditionalPropertiesAnyType {
 
            @Override
            public AdditionalPropertiesAnyType read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java
index 7055b32a017..5252f9e9f37 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java
@@ -133,25 +133,26 @@ public class AdditionalPropertiesArray {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesArray
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesArray
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesArray.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesArray.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesArray is not found in the empty JSON string", AdditionalPropertiesArray.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesArray.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesArray` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesArray` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -177,9 +178,9 @@ public class AdditionalPropertiesArray {
 
            @Override
            public AdditionalPropertiesArray read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java
index 91d91a38b95..0ab06c7e54d 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java
@@ -132,25 +132,26 @@ public class AdditionalPropertiesBoolean {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesBoolean
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesBoolean
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesBoolean.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesBoolean.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesBoolean is not found in the empty JSON string", AdditionalPropertiesBoolean.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesBoolean.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesBoolean` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesBoolean` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -176,9 +177,9 @@ public class AdditionalPropertiesBoolean {
 
            @Override
            public AdditionalPropertiesBoolean read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
index b27b1a665a8..c1cceca6e56 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
@@ -480,25 +480,26 @@ public class AdditionalPropertiesClass {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesClass is not found in the empty JSON string", AdditionalPropertiesClass.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesClass.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesClass` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesClass` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -521,9 +522,9 @@ public class AdditionalPropertiesClass {
 
            @Override
            public AdditionalPropertiesClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java
index 8027268210e..92c9ca7cc50 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java
@@ -132,25 +132,26 @@ public class AdditionalPropertiesInteger {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesInteger
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesInteger
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesInteger.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesInteger.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesInteger is not found in the empty JSON string", AdditionalPropertiesInteger.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesInteger.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesInteger` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesInteger` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -176,9 +177,9 @@ public class AdditionalPropertiesInteger {
 
            @Override
            public AdditionalPropertiesInteger read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java
index abe5f4cc555..f786790043b 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java
@@ -133,25 +133,26 @@ public class AdditionalPropertiesNumber {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesNumber
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesNumber
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesNumber.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesNumber.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesNumber is not found in the empty JSON string", AdditionalPropertiesNumber.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesNumber.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesNumber` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesNumber` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -177,9 +178,9 @@ public class AdditionalPropertiesNumber {
 
            @Override
            public AdditionalPropertiesNumber read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java
index eb3de7bbd95..8d7686e9800 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java
@@ -133,25 +133,26 @@ public class AdditionalPropertiesObject {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesObject
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesObject
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesObject.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesObject.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesObject is not found in the empty JSON string", AdditionalPropertiesObject.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesObject.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesObject` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesObject` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -177,9 +178,9 @@ public class AdditionalPropertiesObject {
 
            @Override
            public AdditionalPropertiesObject read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java
index 7f1bb50e0cf..6dae21f945b 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java
@@ -132,25 +132,26 @@ public class AdditionalPropertiesString {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesString
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesString
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesString.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesString.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesString is not found in the empty JSON string", AdditionalPropertiesString.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesString.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesString` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesString` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -176,9 +177,9 @@ public class AdditionalPropertiesString {
 
            @Override
            public AdditionalPropertiesString read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Animal.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Animal.java
index 88b554bbf2b..15e2aa381e6 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Animal.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Animal.java
@@ -162,28 +162,28 @@ public class Animal {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Animal
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Animal
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Animal.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Animal.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Animal is not found in the empty JSON string", Animal.openapiRequiredFields.toString()));
         }
       }
 
-      String discriminatorValue = jsonObj.get("className").getAsString();
+      String discriminatorValue = jsonElement.getAsJsonObject().get("className").getAsString();
       switch (discriminatorValue) {
         case "BigCat":
-          BigCat.validateJsonObject(jsonObj);
+          BigCat.validateJsonElement(jsonElement);
           break;
         case "Cat":
-          Cat.validateJsonObject(jsonObj);
+          Cat.validateJsonElement(jsonElement);
           break;
         case "Dog":
-          Dog.validateJsonObject(jsonObj);
+          Dog.validateJsonElement(jsonElement);
           break;
         default:
           throw new IllegalArgumentException(String.format("The value of the `className` field `%s` does not match any key defined in the discriminator's mapping.", discriminatorValue));
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
index a8de8fc7f56..58141e11d0b 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
@@ -143,25 +143,26 @@ public class ArrayOfArrayOfNumberOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfArrayOfNumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfArrayOfNumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfArrayOfNumberOnly is not found in the empty JSON string", ArrayOfArrayOfNumberOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ArrayOfArrayOfNumberOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayOfArrayOfNumberOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayOfArrayOfNumberOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("ArrayArrayNumber") != null && !jsonObj.get("ArrayArrayNumber").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `ArrayArrayNumber` to be an array in the JSON string but got `%s`", jsonObj.get("ArrayArrayNumber").toString()));
@@ -188,9 +189,9 @@ public class ArrayOfArrayOfNumberOnly {
 
            @Override
            public ArrayOfArrayOfNumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index 7c9ef3dbb7b..3d05967401c 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -143,25 +143,26 @@ public class ArrayOfNumberOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfNumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfNumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfNumberOnly is not found in the empty JSON string", ArrayOfNumberOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ArrayOfNumberOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayOfNumberOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayOfNumberOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("ArrayNumber") != null && !jsonObj.get("ArrayNumber").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `ArrayNumber` to be an array in the JSON string but got `%s`", jsonObj.get("ArrayNumber").toString()));
@@ -188,9 +189,9 @@ public class ArrayOfNumberOnly {
 
            @Override
            public ArrayOfNumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayTest.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayTest.java
index 458a9aa88f9..111d03b71e9 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayTest.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ArrayTest.java
@@ -215,25 +215,26 @@ public class ArrayTest {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayTest is not found in the empty JSON string", ArrayTest.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ArrayTest.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayTest` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayTest` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("array_of_string") != null && !jsonObj.get("array_of_string").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `array_of_string` to be an array in the JSON string but got `%s`", jsonObj.get("array_of_string").toString()));
@@ -268,9 +269,9 @@ public class ArrayTest {
 
            @Override
            public ArrayTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/BigCat.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/BigCat.java
index 740c2f3b737..fd82762e2e0 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/BigCat.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/BigCat.java
@@ -191,30 +191,30 @@ public class BigCat extends Cat {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to BigCat
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to BigCat
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!BigCat.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!BigCat.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in BigCat is not found in the empty JSON string", BigCat.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!BigCat.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `BigCat` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `BigCat` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : BigCat.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
   }
@@ -239,9 +239,9 @@ public class BigCat extends Cat {
 
            @Override
            public BigCat read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Capitalization.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Capitalization.java
index 6eaa2f1b9f8..6bdb7547b8c 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Capitalization.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Capitalization.java
@@ -272,25 +272,26 @@ public class Capitalization {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Capitalization
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Capitalization
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Capitalization.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Capitalization.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Capitalization is not found in the empty JSON string", Capitalization.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Capitalization.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Capitalization` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Capitalization` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("smallCamel") != null && !jsonObj.get("smallCamel").isJsonNull()) && !jsonObj.get("smallCamel").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `smallCamel` to be a primitive type in the JSON string but got `%s`", jsonObj.get("smallCamel").toString()));
       }
@@ -331,9 +332,9 @@ public class Capitalization {
 
            @Override
            public Capitalization read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Cat.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Cat.java
index d5a738f5344..b523a01e230 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Cat.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Cat.java
@@ -139,22 +139,22 @@ public class Cat extends Animal {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Cat
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Cat
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Cat.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Cat.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Cat is not found in the empty JSON string", Cat.openapiRequiredFields.toString()));
         }
       }
 
-      String discriminatorValue = jsonObj.get("className").getAsString();
+      String discriminatorValue = jsonElement.getAsJsonObject().get("className").getAsString();
       switch (discriminatorValue) {
         case "BigCat":
-          BigCat.validateJsonObject(jsonObj);
+          BigCat.validateJsonElement(jsonElement);
           break;
         default:
           throw new IllegalArgumentException(String.format("The value of the `className` field `%s` does not match any key defined in the discriminator's mapping.", discriminatorValue));
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Category.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Category.java
index 106fcefb378..bcdcbaa42ef 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Category.java
@@ -161,32 +161,33 @@ public class Category {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Category.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Category` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Category` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Category.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -212,9 +213,9 @@ public class Category {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ClassModel.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ClassModel.java
index 9532dfa3870..61c6ac4e1e9 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ClassModel.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ClassModel.java
@@ -132,25 +132,26 @@ public class ClassModel {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ClassModel
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ClassModel
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ClassModel.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ClassModel.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ClassModel is not found in the empty JSON string", ClassModel.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ClassModel.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ClassModel` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ClassModel` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("_class") != null && !jsonObj.get("_class").isJsonNull()) && !jsonObj.get("_class").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `_class` to be a primitive type in the JSON string but got `%s`", jsonObj.get("_class").toString()));
       }
@@ -176,9 +177,9 @@ public class ClassModel {
 
            @Override
            public ClassModel read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Client.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Client.java
index eaf9c719f7b..dd16290d102 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Client.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Client.java
@@ -132,25 +132,26 @@ public class Client {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Client
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Client
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Client.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Client.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Client is not found in the empty JSON string", Client.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Client.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Client` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Client` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("client") != null && !jsonObj.get("client").isJsonNull()) && !jsonObj.get("client").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `client` to be a primitive type in the JSON string but got `%s`", jsonObj.get("client").toString()));
       }
@@ -176,9 +177,9 @@ public class Client {
 
            @Override
            public Client read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Dog.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Dog.java
index 96156f08fe3..b53d263b1e9 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Dog.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Dog.java
@@ -139,30 +139,30 @@ public class Dog extends Animal {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Dog
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Dog
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Dog.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Dog.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Dog is not found in the empty JSON string", Dog.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Dog.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Dog` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Dog` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Dog.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
   }
@@ -187,9 +187,9 @@ public class Dog extends Animal {
 
            @Override
            public Dog read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/EnumArrays.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/EnumArrays.java
index 9980488e8ec..92fa18a6c13 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/EnumArrays.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/EnumArrays.java
@@ -264,25 +264,26 @@ public class EnumArrays {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to EnumArrays
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to EnumArrays
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!EnumArrays.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!EnumArrays.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in EnumArrays is not found in the empty JSON string", EnumArrays.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!EnumArrays.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `EnumArrays` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `EnumArrays` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("just_symbol") != null && !jsonObj.get("just_symbol").isJsonNull()) && !jsonObj.get("just_symbol").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `just_symbol` to be a primitive type in the JSON string but got `%s`", jsonObj.get("just_symbol").toString()));
       }
@@ -312,9 +313,9 @@ public class EnumArrays {
 
            @Override
            public EnumArrays read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/EnumTest.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/EnumTest.java
index f63987dac1c..b279ba5012d 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/EnumTest.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/EnumTest.java
@@ -438,32 +438,33 @@ public class EnumTest {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to EnumTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to EnumTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!EnumTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!EnumTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in EnumTest is not found in the empty JSON string", EnumTest.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!EnumTest.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `EnumTest` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `EnumTest` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : EnumTest.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("enum_string") != null && !jsonObj.get("enum_string").isJsonNull()) && !jsonObj.get("enum_string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `enum_string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("enum_string").toString()));
       }
@@ -492,9 +493,9 @@ public class EnumTest {
 
            @Override
            public EnumTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
index 4505754cafe..ed74eecc4bc 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
@@ -171,28 +171,29 @@ public class FileSchemaTestClass {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to FileSchemaTestClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to FileSchemaTestClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!FileSchemaTestClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!FileSchemaTestClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in FileSchemaTestClass is not found in the empty JSON string", FileSchemaTestClass.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!FileSchemaTestClass.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `FileSchemaTestClass` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `FileSchemaTestClass` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `file`
       if (jsonObj.get("file") != null && !jsonObj.get("file").isJsonNull()) {
-        ModelFile.validateJsonObject(jsonObj.getAsJsonObject("file"));
+        ModelFile.validateJsonElement(jsonObj.get("file"));
       }
       if (jsonObj.get("files") != null && !jsonObj.get("files").isJsonNull()) {
         JsonArray jsonArrayfiles = jsonObj.getAsJsonArray("files");
@@ -204,7 +205,7 @@ public class FileSchemaTestClass {
 
           // validate the optional field `files` (array)
           for (int i = 0; i < jsonArrayfiles.size(); i++) {
-            ModelFile.validateJsonObject(jsonArrayfiles.get(i).getAsJsonObject());
+            ModelFile.validateJsonElement(jsonArrayfiles.get(i));
           };
         }
       }
@@ -230,9 +231,9 @@ public class FileSchemaTestClass {
 
            @Override
            public FileSchemaTestClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/FormatTest.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/FormatTest.java
index d8b97517934..bbe855488fd 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/FormatTest.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/FormatTest.java
@@ -515,32 +515,33 @@ public class FormatTest {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to FormatTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to FormatTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!FormatTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!FormatTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in FormatTest is not found in the empty JSON string", FormatTest.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!FormatTest.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `FormatTest` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `FormatTest` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : FormatTest.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("string") != null && !jsonObj.get("string").isJsonNull()) && !jsonObj.get("string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("string").toString()));
       }
@@ -572,9 +573,9 @@ public class FormatTest {
 
            @Override
            public FormatTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
index e6c2d774dac..23889a40b13 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
@@ -152,25 +152,26 @@ public class HasOnlyReadOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to HasOnlyReadOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to HasOnlyReadOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!HasOnlyReadOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!HasOnlyReadOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in HasOnlyReadOnly is not found in the empty JSON string", HasOnlyReadOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!HasOnlyReadOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `HasOnlyReadOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `HasOnlyReadOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("bar") != null && !jsonObj.get("bar").isJsonNull()) && !jsonObj.get("bar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `bar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("bar").toString()));
       }
@@ -199,9 +200,9 @@ public class HasOnlyReadOnly {
 
            @Override
            public HasOnlyReadOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/MapTest.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/MapTest.java
index 77765a85fcc..36e9d8420c1 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/MapTest.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/MapTest.java
@@ -297,25 +297,26 @@ public class MapTest {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to MapTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to MapTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!MapTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!MapTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in MapTest is not found in the empty JSON string", MapTest.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!MapTest.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `MapTest` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `MapTest` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -338,9 +339,9 @@ public class MapTest {
 
            @Override
            public MapTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
index 7037c8bb425..abc1913bc31 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
@@ -201,25 +201,26 @@ public class MixedPropertiesAndAdditionalPropertiesClass {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to MixedPropertiesAndAdditionalPropertiesClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to MixedPropertiesAndAdditionalPropertiesClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in MixedPropertiesAndAdditionalPropertiesClass is not found in the empty JSON string", MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!MixedPropertiesAndAdditionalPropertiesClass.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `MixedPropertiesAndAdditionalPropertiesClass` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `MixedPropertiesAndAdditionalPropertiesClass` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("uuid") != null && !jsonObj.get("uuid").isJsonNull()) && !jsonObj.get("uuid").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `uuid` to be a primitive type in the JSON string but got `%s`", jsonObj.get("uuid").toString()));
       }
@@ -245,9 +246,9 @@ public class MixedPropertiesAndAdditionalPropertiesClass {
 
            @Override
            public MixedPropertiesAndAdditionalPropertiesClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Model200Response.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Model200Response.java
index c64699c5d35..6cf2fa641b8 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Model200Response.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Model200Response.java
@@ -160,25 +160,26 @@ public class Model200Response {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Model200Response
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Model200Response
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Model200Response.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Model200Response.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Model200Response is not found in the empty JSON string", Model200Response.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Model200Response.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Model200Response` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Model200Response` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("class") != null && !jsonObj.get("class").isJsonNull()) && !jsonObj.get("class").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `class` to be a primitive type in the JSON string but got `%s`", jsonObj.get("class").toString()));
       }
@@ -204,9 +205,9 @@ public class Model200Response {
 
            @Override
            public Model200Response read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelApiResponse.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelApiResponse.java
index cd745ea7195..052e952c6d8 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelApiResponse.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelApiResponse.java
@@ -188,25 +188,26 @@ public class ModelApiResponse {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelApiResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelApiResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelApiResponse is not found in the empty JSON string", ModelApiResponse.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ModelApiResponse.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelApiResponse` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelApiResponse` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -235,9 +236,9 @@ public class ModelApiResponse {
 
            @Override
            public ModelApiResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelFile.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelFile.java
index ad041d9d3c7..b7e2becb181 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelFile.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelFile.java
@@ -132,25 +132,26 @@ public class ModelFile {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelFile
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelFile
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelFile.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelFile.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelFile is not found in the empty JSON string", ModelFile.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ModelFile.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelFile` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelFile` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("sourceURI") != null && !jsonObj.get("sourceURI").isJsonNull()) && !jsonObj.get("sourceURI").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `sourceURI` to be a primitive type in the JSON string but got `%s`", jsonObj.get("sourceURI").toString()));
       }
@@ -176,9 +177,9 @@ public class ModelFile {
 
            @Override
            public ModelFile read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelList.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelList.java
index 3ba2c2dfb1e..7916cc3e58f 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelList.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelList.java
@@ -132,25 +132,26 @@ public class ModelList {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelList
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelList
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelList.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelList.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelList is not found in the empty JSON string", ModelList.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ModelList.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelList` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelList` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("123-list") != null && !jsonObj.get("123-list").isJsonNull()) && !jsonObj.get("123-list").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `123-list` to be a primitive type in the JSON string but got `%s`", jsonObj.get("123-list").toString()));
       }
@@ -176,9 +177,9 @@ public class ModelList {
 
            @Override
            public ModelList read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelReturn.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelReturn.java
index b6ad470b979..132dcbd8cc0 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelReturn.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ModelReturn.java
@@ -132,25 +132,26 @@ public class ModelReturn {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelReturn
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelReturn
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelReturn.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelReturn.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelReturn is not found in the empty JSON string", ModelReturn.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ModelReturn.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelReturn` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelReturn` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -173,9 +174,9 @@ public class ModelReturn {
 
            @Override
            public ModelReturn read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Name.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Name.java
index dbc582f81da..ff66cd8879e 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Name.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Name.java
@@ -209,32 +209,33 @@ public class Name {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Name
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Name
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Name.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Name.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Name is not found in the empty JSON string", Name.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Name.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Name` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Name` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Name.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("property") != null && !jsonObj.get("property").isJsonNull()) && !jsonObj.get("property").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `property` to be a primitive type in the JSON string but got `%s`", jsonObj.get("property").toString()));
       }
@@ -260,9 +261,9 @@ public class Name {
 
            @Override
            public Name read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/NumberOnly.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/NumberOnly.java
index 9ab12af4256..8106cf27186 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/NumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/NumberOnly.java
@@ -133,25 +133,26 @@ public class NumberOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to NumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to NumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!NumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!NumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in NumberOnly is not found in the empty JSON string", NumberOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!NumberOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `NumberOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `NumberOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -174,9 +175,9 @@ public class NumberOnly {
 
            @Override
            public NumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Order.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Order.java
index 83b3c7f4694..3df944ca297 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Order.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Order.java
@@ -322,25 +322,26 @@ public class Order {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Order
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Order
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Order is not found in the empty JSON string", Order.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Order.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Order` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Order` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
       }
@@ -366,9 +367,9 @@ public class Order {
 
            @Override
            public Order read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/OuterComposite.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/OuterComposite.java
index 571948d8d84..923989b00e3 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/OuterComposite.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/OuterComposite.java
@@ -189,25 +189,26 @@ public class OuterComposite {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to OuterComposite
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to OuterComposite
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!OuterComposite.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!OuterComposite.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in OuterComposite is not found in the empty JSON string", OuterComposite.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!OuterComposite.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `OuterComposite` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `OuterComposite` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("my_string") != null && !jsonObj.get("my_string").isJsonNull()) && !jsonObj.get("my_string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `my_string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("my_string").toString()));
       }
@@ -233,9 +234,9 @@ public class OuterComposite {
 
            @Override
            public OuterComposite read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Pet.java
index 1cf99a5e284..079d211ecd7 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Pet.java
@@ -345,35 +345,36 @@ public class Pet {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Pet.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Pet` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Pet` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -394,7 +395,7 @@ public class Pet {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -423,9 +424,9 @@ public class Pet {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
index d68f24e4f02..6a0f5f2a4ee 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
@@ -159,25 +159,26 @@ public class ReadOnlyFirst {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ReadOnlyFirst
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ReadOnlyFirst
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ReadOnlyFirst.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ReadOnlyFirst.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ReadOnlyFirst is not found in the empty JSON string", ReadOnlyFirst.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ReadOnlyFirst.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ReadOnlyFirst` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ReadOnlyFirst` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("bar") != null && !jsonObj.get("bar").isJsonNull()) && !jsonObj.get("bar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `bar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("bar").toString()));
       }
@@ -206,9 +207,9 @@ public class ReadOnlyFirst {
 
            @Override
            public ReadOnlyFirst read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/SpecialModelName.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/SpecialModelName.java
index 39085e3f776..fbd72eb8d90 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/SpecialModelName.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/SpecialModelName.java
@@ -132,25 +132,26 @@ public class SpecialModelName {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to SpecialModelName
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to SpecialModelName
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!SpecialModelName.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!SpecialModelName.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in SpecialModelName is not found in the empty JSON string", SpecialModelName.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!SpecialModelName.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `SpecialModelName` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `SpecialModelName` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -173,9 +174,9 @@ public class SpecialModelName {
 
            @Override
            public SpecialModelName read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Tag.java
index 43e5e0fab51..dd815aaeec8 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/Tag.java
@@ -160,25 +160,26 @@ public class Tag {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Tag.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Tag` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Tag` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -204,9 +205,9 @@ public class Tag {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/TypeHolderDefault.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
index bc20cdf5b3b..8c09e9cdd3d 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
@@ -260,32 +260,33 @@ public class TypeHolderDefault {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to TypeHolderDefault
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to TypeHolderDefault
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!TypeHolderDefault.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!TypeHolderDefault.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in TypeHolderDefault is not found in the empty JSON string", TypeHolderDefault.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!TypeHolderDefault.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TypeHolderDefault` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TypeHolderDefault` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : TypeHolderDefault.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("string_item").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `string_item` to be a primitive type in the JSON string but got `%s`", jsonObj.get("string_item").toString()));
       }
@@ -317,9 +318,9 @@ public class TypeHolderDefault {
 
            @Override
            public TypeHolderDefault read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/TypeHolderExample.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/TypeHolderExample.java
index 931fe392e9c..09314d51c35 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/TypeHolderExample.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/TypeHolderExample.java
@@ -289,32 +289,33 @@ public class TypeHolderExample {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to TypeHolderExample
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to TypeHolderExample
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!TypeHolderExample.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!TypeHolderExample.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in TypeHolderExample is not found in the empty JSON string", TypeHolderExample.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!TypeHolderExample.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TypeHolderExample` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TypeHolderExample` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : TypeHolderExample.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("string_item").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `string_item` to be a primitive type in the JSON string but got `%s`", jsonObj.get("string_item").toString()));
       }
@@ -346,9 +347,9 @@ public class TypeHolderExample {
 
            @Override
            public TypeHolderExample read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/User.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/User.java
index 4a518308934..ddfa460ef48 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/User.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/User.java
@@ -328,25 +328,26 @@ public class User {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to User
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to User
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in User is not found in the empty JSON string", User.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!User.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `User` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `User` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("username") != null && !jsonObj.get("username").isJsonNull()) && !jsonObj.get("username").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `username` to be a primitive type in the JSON string but got `%s`", jsonObj.get("username").toString()));
       }
@@ -387,9 +388,9 @@ public class User {
 
            @Override
            public User read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/XmlItem.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/XmlItem.java
index 825fd011889..51ed8c3b949 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/XmlItem.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/model/XmlItem.java
@@ -991,25 +991,26 @@ public class XmlItem {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to XmlItem
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to XmlItem
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!XmlItem.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!XmlItem.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in XmlItem is not found in the empty JSON string", XmlItem.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!XmlItem.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `XmlItem` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `XmlItem` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("attribute_string") != null && !jsonObj.get("attribute_string").isJsonNull()) && !jsonObj.get("attribute_string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `attribute_string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("attribute_string").toString()));
       }
@@ -1083,9 +1084,9 @@ public class XmlItem {
 
            @Override
            public XmlItem read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Category.java b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Category.java
index 3ecdbda0716..5aef445f0cf 100644
--- a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Category.java
@@ -206,17 +206,18 @@ public class Category {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -259,8 +260,9 @@ public class Category {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Category instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/ModelApiResponse.java b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/ModelApiResponse.java
index 135ecf70fc0..f4f09dbfb17 100644
--- a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/ModelApiResponse.java
+++ b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/ModelApiResponse.java
@@ -234,17 +234,18 @@ public class ModelApiResponse {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelApiResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelApiResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelApiResponse is not found in the empty JSON string", ModelApiResponse.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -290,8 +291,9 @@ public class ModelApiResponse {
 
            @Override
            public ModelApiResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelApiResponse instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Order.java b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Order.java
index f5abae46523..004059b8f76 100644
--- a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Order.java
+++ b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Order.java
@@ -368,17 +368,18 @@ public class Order {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Order
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Order
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Order is not found in the empty JSON string", Order.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
       }
@@ -421,8 +422,9 @@ public class Order {
 
            @Override
            public Order read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Order instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Pet.java
index 39ba8d3643f..54d44c9c469 100644
--- a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Pet.java
@@ -394,27 +394,28 @@ public class Pet {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -435,7 +436,7 @@ public class Pet {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -481,8 +482,9 @@ public class Pet {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Pet instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Tag.java
index 9c1f9247b1b..97fe598e2e1 100644
--- a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/Tag.java
@@ -206,17 +206,18 @@ public class Tag {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -259,8 +260,9 @@ public class Tag {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Tag instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/User.java b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/User.java
index 2008add2959..f7aa406f479 100644
--- a/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/User.java
+++ b/samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/model/User.java
@@ -374,17 +374,18 @@ public class User {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to User
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to User
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in User is not found in the empty JSON string", User.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("username") != null && !jsonObj.get("username").isJsonNull()) && !jsonObj.get("username").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `username` to be a primitive type in the JSON string but got `%s`", jsonObj.get("username").toString()));
       }
@@ -442,8 +443,9 @@ public class User {
 
            @Override
            public User read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              User instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Category.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Category.java
index 3ecdbda0716..5aef445f0cf 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Category.java
@@ -206,17 +206,18 @@ public class Category {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -259,8 +260,9 @@ public class Category {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Category instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/ModelApiResponse.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/ModelApiResponse.java
index 135ecf70fc0..f4f09dbfb17 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/ModelApiResponse.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/ModelApiResponse.java
@@ -234,17 +234,18 @@ public class ModelApiResponse {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelApiResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelApiResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelApiResponse is not found in the empty JSON string", ModelApiResponse.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -290,8 +291,9 @@ public class ModelApiResponse {
 
            @Override
            public ModelApiResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelApiResponse instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Order.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Order.java
index f5abae46523..004059b8f76 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Order.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Order.java
@@ -368,17 +368,18 @@ public class Order {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Order
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Order
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Order is not found in the empty JSON string", Order.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
       }
@@ -421,8 +422,9 @@ public class Order {
 
            @Override
            public Order read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Order instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Pet.java
index 39ba8d3643f..54d44c9c469 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Pet.java
@@ -394,27 +394,28 @@ public class Pet {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -435,7 +436,7 @@ public class Pet {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -481,8 +482,9 @@ public class Pet {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Pet instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/PetWithRequiredNullableCases1.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/PetWithRequiredNullableCases1.java
index 165d38c65ed..d1839c9317e 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/PetWithRequiredNullableCases1.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/PetWithRequiredNullableCases1.java
@@ -406,27 +406,28 @@ public class PetWithRequiredNullableCases1 {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to PetWithRequiredNullableCases1
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to PetWithRequiredNullableCases1
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!PetWithRequiredNullableCases1.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!PetWithRequiredNullableCases1.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in PetWithRequiredNullableCases1 is not found in the empty JSON string", PetWithRequiredNullableCases1.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : PetWithRequiredNullableCases1.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -447,7 +448,7 @@ public class PetWithRequiredNullableCases1 {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -493,8 +494,9 @@ public class PetWithRequiredNullableCases1 {
 
            @Override
            public PetWithRequiredNullableCases1 read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              PetWithRequiredNullableCases1 instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/PetWithRequiredNullableCases2.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/PetWithRequiredNullableCases2.java
index 8bea0cee0b0..7cf21a818f9 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/PetWithRequiredNullableCases2.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/PetWithRequiredNullableCases2.java
@@ -394,27 +394,28 @@ public class PetWithRequiredNullableCases2 {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to PetWithRequiredNullableCases2
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to PetWithRequiredNullableCases2
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!PetWithRequiredNullableCases2.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!PetWithRequiredNullableCases2.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in PetWithRequiredNullableCases2 is not found in the empty JSON string", PetWithRequiredNullableCases2.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : PetWithRequiredNullableCases2.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -435,7 +436,7 @@ public class PetWithRequiredNullableCases2 {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -481,8 +482,9 @@ public class PetWithRequiredNullableCases2 {
 
            @Override
            public PetWithRequiredNullableCases2 read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              PetWithRequiredNullableCases2 instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Tag.java
index 9c1f9247b1b..97fe598e2e1 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/Tag.java
@@ -206,17 +206,18 @@ public class Tag {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -259,8 +260,9 @@ public class Tag {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Tag instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/User.java b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/User.java
index 2008add2959..f7aa406f479 100644
--- a/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/User.java
+++ b/samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/model/User.java
@@ -374,17 +374,18 @@ public class User {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to User
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to User
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in User is not found in the empty JSON string", User.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("username") != null && !jsonObj.get("username").isJsonNull()) && !jsonObj.get("username").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `username` to be a primitive type in the JSON string but got `%s`", jsonObj.get("username").toString()));
       }
@@ -442,8 +443,9 @@ public class User {
 
            @Override
            public User read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              User instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/docs/FakeApi.md b/samples/client/petstore/java/okhttp-gson-parcelableModel/docs/FakeApi.md
index 98f0b0098b8..0736ffc044d 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/docs/FakeApi.md
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/docs/FakeApi.md
@@ -251,7 +251,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java
index 2c09483bb2f..8d642af57bf 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesAnyType.java
@@ -155,25 +155,26 @@ public class AdditionalPropertiesAnyType implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesAnyType
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesAnyType
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesAnyType.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesAnyType.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesAnyType is not found in the empty JSON string", AdditionalPropertiesAnyType.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesAnyType.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesAnyType` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesAnyType` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -199,9 +200,9 @@ public class AdditionalPropertiesAnyType implements Parcelable {
 
            @Override
            public AdditionalPropertiesAnyType read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java
index b2e9ab096a4..fe46853e434 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesArray.java
@@ -156,25 +156,26 @@ public class AdditionalPropertiesArray implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesArray
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesArray
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesArray.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesArray.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesArray is not found in the empty JSON string", AdditionalPropertiesArray.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesArray.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesArray` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesArray` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -200,9 +201,9 @@ public class AdditionalPropertiesArray implements Parcelable {
 
            @Override
            public AdditionalPropertiesArray read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java
index f01c877c557..aa666774ec5 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesBoolean.java
@@ -155,25 +155,26 @@ public class AdditionalPropertiesBoolean implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesBoolean
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesBoolean
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesBoolean.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesBoolean.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesBoolean is not found in the empty JSON string", AdditionalPropertiesBoolean.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesBoolean.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesBoolean` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesBoolean` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -199,9 +200,9 @@ public class AdditionalPropertiesBoolean implements Parcelable {
 
            @Override
            public AdditionalPropertiesBoolean read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
index d35eaeca5dc..eda493d4032 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
@@ -475,7 +475,7 @@ public class AdditionalPropertiesClass implements Parcelable {
 
   AdditionalPropertiesClass(Parcel in) {
     mapString = (Map<String, String>)in.readValue(null);
-    mapNumber = (Map<String, BigDecimal>)in.readValue(BigDecimal.class.getClassLoader());
+    mapNumber = (Map<String, BigDecimal>)in.readValue(null);
     mapInteger = (Map<String, Integer>)in.readValue(null);
     mapBoolean = (Map<String, Boolean>)in.readValue(null);
     mapArrayInteger = (Map<String, List<Integer>>)in.readValue(List.class.getClassLoader());
@@ -523,25 +523,26 @@ public class AdditionalPropertiesClass implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesClass is not found in the empty JSON string", AdditionalPropertiesClass.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesClass.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesClass` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesClass` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -564,9 +565,9 @@ public class AdditionalPropertiesClass implements Parcelable {
 
            @Override
            public AdditionalPropertiesClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java
index f70996848af..590b21a6a18 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesInteger.java
@@ -155,25 +155,26 @@ public class AdditionalPropertiesInteger implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesInteger
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesInteger
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesInteger.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesInteger.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesInteger is not found in the empty JSON string", AdditionalPropertiesInteger.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesInteger.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesInteger` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesInteger` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -199,9 +200,9 @@ public class AdditionalPropertiesInteger implements Parcelable {
 
            @Override
            public AdditionalPropertiesInteger read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java
index 505f67c4c1d..95c0c465ad8 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesNumber.java
@@ -156,25 +156,26 @@ public class AdditionalPropertiesNumber implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesNumber
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesNumber
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesNumber.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesNumber.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesNumber is not found in the empty JSON string", AdditionalPropertiesNumber.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesNumber.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesNumber` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesNumber` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -200,9 +201,9 @@ public class AdditionalPropertiesNumber implements Parcelable {
 
            @Override
            public AdditionalPropertiesNumber read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java
index 0a334eb4450..d6179b5e062 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesObject.java
@@ -156,25 +156,26 @@ public class AdditionalPropertiesObject implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesObject
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesObject
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesObject.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesObject.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesObject is not found in the empty JSON string", AdditionalPropertiesObject.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesObject.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesObject` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesObject` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -200,9 +201,9 @@ public class AdditionalPropertiesObject implements Parcelable {
 
            @Override
            public AdditionalPropertiesObject read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java
index 3bb42ab64c4..a01f05e1b2b 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/AdditionalPropertiesString.java
@@ -155,25 +155,26 @@ public class AdditionalPropertiesString implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesString
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesString
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesString.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesString.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesString is not found in the empty JSON string", AdditionalPropertiesString.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AdditionalPropertiesString.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesString` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AdditionalPropertiesString` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -199,9 +200,9 @@ public class AdditionalPropertiesString implements Parcelable {
 
            @Override
            public AdditionalPropertiesString read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Animal.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Animal.java
index 10adfe83252..3ad111c16dd 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Animal.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Animal.java
@@ -187,28 +187,28 @@ public class Animal implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Animal
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Animal
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Animal.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Animal.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Animal is not found in the empty JSON string", Animal.openapiRequiredFields.toString()));
         }
       }
 
-      String discriminatorValue = jsonObj.get("className").getAsString();
+      String discriminatorValue = jsonElement.getAsJsonObject().get("className").getAsString();
       switch (discriminatorValue) {
         case "BigCat":
-          BigCat.validateJsonObject(jsonObj);
+          BigCat.validateJsonElement(jsonElement);
           break;
         case "Cat":
-          Cat.validateJsonObject(jsonObj);
+          Cat.validateJsonElement(jsonElement);
           break;
         case "Dog":
-          Dog.validateJsonObject(jsonObj);
+          Dog.validateJsonElement(jsonElement);
           break;
         default:
           throw new IllegalArgumentException(String.format("The value of the `className` field `%s` does not match any key defined in the discriminator's mapping.", discriminatorValue));
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
index 2de2ddb34b1..9568e053415 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
@@ -166,25 +166,26 @@ public class ArrayOfArrayOfNumberOnly implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfArrayOfNumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfArrayOfNumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfArrayOfNumberOnly is not found in the empty JSON string", ArrayOfArrayOfNumberOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ArrayOfArrayOfNumberOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayOfArrayOfNumberOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayOfArrayOfNumberOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("ArrayArrayNumber") != null && !jsonObj.get("ArrayArrayNumber").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `ArrayArrayNumber` to be an array in the JSON string but got `%s`", jsonObj.get("ArrayArrayNumber").toString()));
@@ -211,9 +212,9 @@ public class ArrayOfArrayOfNumberOnly implements Parcelable {
 
            @Override
            public ArrayOfArrayOfNumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index a1c42d7fdf2..455f0446f31 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -137,7 +137,7 @@ public class ArrayOfNumberOnly implements Parcelable {
   }
 
   ArrayOfNumberOnly(Parcel in) {
-    arrayNumber = (List<BigDecimal>)in.readValue(BigDecimal.class.getClassLoader());
+    arrayNumber = (List<BigDecimal>)in.readValue(null);
   }
 
   public int describeContents() {
@@ -166,25 +166,26 @@ public class ArrayOfNumberOnly implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfNumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfNumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfNumberOnly is not found in the empty JSON string", ArrayOfNumberOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ArrayOfNumberOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayOfNumberOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayOfNumberOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("ArrayNumber") != null && !jsonObj.get("ArrayNumber").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `ArrayNumber` to be an array in the JSON string but got `%s`", jsonObj.get("ArrayNumber").toString()));
@@ -211,9 +212,9 @@ public class ArrayOfNumberOnly implements Parcelable {
 
            @Override
            public ArrayOfNumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayTest.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayTest.java
index 5319e4fef22..2a3bd88782f 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayTest.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ArrayTest.java
@@ -242,25 +242,26 @@ public class ArrayTest implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayTest is not found in the empty JSON string", ArrayTest.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ArrayTest.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayTest` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ArrayTest` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("array_of_string") != null && !jsonObj.get("array_of_string").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `array_of_string` to be an array in the JSON string but got `%s`", jsonObj.get("array_of_string").toString()));
@@ -295,9 +296,9 @@ public class ArrayTest implements Parcelable {
 
            @Override
            public ArrayTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/BigCat.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/BigCat.java
index ff134797efd..f481969ee2b 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/BigCat.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/BigCat.java
@@ -217,30 +217,30 @@ public class BigCat extends Cat implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to BigCat
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to BigCat
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!BigCat.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!BigCat.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in BigCat is not found in the empty JSON string", BigCat.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!BigCat.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `BigCat` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `BigCat` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : BigCat.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
   }
@@ -265,9 +265,9 @@ public class BigCat extends Cat implements Parcelable {
 
            @Override
            public BigCat read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Capitalization.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Capitalization.java
index b845a0916b9..c0950b22581 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Capitalization.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Capitalization.java
@@ -305,25 +305,26 @@ public class Capitalization implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Capitalization
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Capitalization
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Capitalization.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Capitalization.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Capitalization is not found in the empty JSON string", Capitalization.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Capitalization.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Capitalization` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Capitalization` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("smallCamel") != null && !jsonObj.get("smallCamel").isJsonNull()) && !jsonObj.get("smallCamel").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `smallCamel` to be a primitive type in the JSON string but got `%s`", jsonObj.get("smallCamel").toString()));
       }
@@ -364,9 +365,9 @@ public class Capitalization implements Parcelable {
 
            @Override
            public Capitalization read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Cat.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Cat.java
index 0bba8095754..4e19977b34a 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Cat.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Cat.java
@@ -165,22 +165,22 @@ public class Cat extends Animal implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Cat
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Cat
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Cat.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Cat.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Cat is not found in the empty JSON string", Cat.openapiRequiredFields.toString()));
         }
       }
 
-      String discriminatorValue = jsonObj.get("className").getAsString();
+      String discriminatorValue = jsonElement.getAsJsonObject().get("className").getAsString();
       switch (discriminatorValue) {
         case "BigCat":
-          BigCat.validateJsonObject(jsonObj);
+          BigCat.validateJsonElement(jsonElement);
           break;
         default:
           throw new IllegalArgumentException(String.format("The value of the `className` field `%s` does not match any key defined in the discriminator's mapping.", discriminatorValue));
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Category.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Category.java
index 676aac4b71e..6d66825be4c 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Category.java
@@ -186,32 +186,33 @@ public class Category implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Category.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Category` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Category` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Category.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -237,9 +238,9 @@ public class Category implements Parcelable {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ClassModel.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ClassModel.java
index bc369c13720..6be5c6349c8 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ClassModel.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ClassModel.java
@@ -155,25 +155,26 @@ public class ClassModel implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ClassModel
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ClassModel
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ClassModel.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ClassModel.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ClassModel is not found in the empty JSON string", ClassModel.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ClassModel.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ClassModel` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ClassModel` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("_class") != null && !jsonObj.get("_class").isJsonNull()) && !jsonObj.get("_class").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `_class` to be a primitive type in the JSON string but got `%s`", jsonObj.get("_class").toString()));
       }
@@ -199,9 +200,9 @@ public class ClassModel implements Parcelable {
 
            @Override
            public ClassModel read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Client.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Client.java
index 4969cd52e8c..6f91506b1f1 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Client.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Client.java
@@ -155,25 +155,26 @@ public class Client implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Client
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Client
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Client.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Client.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Client is not found in the empty JSON string", Client.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Client.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Client` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Client` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("client") != null && !jsonObj.get("client").isJsonNull()) && !jsonObj.get("client").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `client` to be a primitive type in the JSON string but got `%s`", jsonObj.get("client").toString()));
       }
@@ -199,9 +200,9 @@ public class Client implements Parcelable {
 
            @Override
            public Client read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Dog.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Dog.java
index fbdece54bd1..93b741aa111 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Dog.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Dog.java
@@ -165,30 +165,30 @@ public class Dog extends Animal implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Dog
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Dog
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Dog.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Dog.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Dog is not found in the empty JSON string", Dog.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Dog.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Dog` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Dog` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Dog.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
   }
@@ -213,9 +213,9 @@ public class Dog extends Animal implements Parcelable {
 
            @Override
            public Dog read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/EnumArrays.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/EnumArrays.java
index 0eb7faa4530..a8761834d36 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/EnumArrays.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/EnumArrays.java
@@ -289,25 +289,26 @@ public class EnumArrays implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to EnumArrays
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to EnumArrays
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!EnumArrays.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!EnumArrays.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in EnumArrays is not found in the empty JSON string", EnumArrays.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!EnumArrays.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `EnumArrays` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `EnumArrays` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("just_symbol") != null && !jsonObj.get("just_symbol").isJsonNull()) && !jsonObj.get("just_symbol").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `just_symbol` to be a primitive type in the JSON string but got `%s`", jsonObj.get("just_symbol").toString()));
       }
@@ -337,9 +338,9 @@ public class EnumArrays implements Parcelable {
 
            @Override
            public EnumArrays read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/EnumTest.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/EnumTest.java
index 32547e0ed23..34dae2aca48 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/EnumTest.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/EnumTest.java
@@ -469,32 +469,33 @@ public class EnumTest implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to EnumTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to EnumTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!EnumTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!EnumTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in EnumTest is not found in the empty JSON string", EnumTest.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!EnumTest.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `EnumTest` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `EnumTest` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : EnumTest.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("enum_string") != null && !jsonObj.get("enum_string").isJsonNull()) && !jsonObj.get("enum_string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `enum_string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("enum_string").toString()));
       }
@@ -523,9 +524,9 @@ public class EnumTest implements Parcelable {
 
            @Override
            public EnumTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
index 47744eb42aa..9635757715c 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
@@ -196,28 +196,29 @@ public class FileSchemaTestClass implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to FileSchemaTestClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to FileSchemaTestClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!FileSchemaTestClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!FileSchemaTestClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in FileSchemaTestClass is not found in the empty JSON string", FileSchemaTestClass.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!FileSchemaTestClass.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `FileSchemaTestClass` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `FileSchemaTestClass` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `file`
       if (jsonObj.get("file") != null && !jsonObj.get("file").isJsonNull()) {
-        ModelFile.validateJsonObject(jsonObj.getAsJsonObject("file"));
+        ModelFile.validateJsonElement(jsonObj.get("file"));
       }
       if (jsonObj.get("files") != null && !jsonObj.get("files").isJsonNull()) {
         JsonArray jsonArrayfiles = jsonObj.getAsJsonArray("files");
@@ -229,7 +230,7 @@ public class FileSchemaTestClass implements Parcelable {
 
           // validate the optional field `files` (array)
           for (int i = 0; i < jsonArrayfiles.size(); i++) {
-            ModelFile.validateJsonObject(jsonArrayfiles.get(i).getAsJsonObject());
+            ModelFile.validateJsonElement(jsonArrayfiles.get(i));
           };
         }
       }
@@ -255,9 +256,9 @@ public class FileSchemaTestClass implements Parcelable {
 
            @Override
            public FileSchemaTestClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/FormatTest.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/FormatTest.java
index 28c3bfdea6f..63115ddd226 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/FormatTest.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/FormatTest.java
@@ -508,7 +508,7 @@ public class FormatTest implements Parcelable {
     integer = (Integer)in.readValue(null);
     int32 = (Integer)in.readValue(null);
     int64 = (Long)in.readValue(null);
-    number = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    number = (BigDecimal)in.readValue(null);
     _float = (Float)in.readValue(null);
     _double = (Double)in.readValue(null);
     string = (String)in.readValue(null);
@@ -518,7 +518,7 @@ public class FormatTest implements Parcelable {
     dateTime = (OffsetDateTime)in.readValue(OffsetDateTime.class.getClassLoader());
     uuid = (UUID)in.readValue(UUID.class.getClassLoader());
     password = (String)in.readValue(null);
-    bigDecimal = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    bigDecimal = (BigDecimal)in.readValue(null);
   }
 
   public int describeContents() {
@@ -564,32 +564,33 @@ public class FormatTest implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to FormatTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to FormatTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!FormatTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!FormatTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in FormatTest is not found in the empty JSON string", FormatTest.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!FormatTest.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `FormatTest` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `FormatTest` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : FormatTest.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("string") != null && !jsonObj.get("string").isJsonNull()) && !jsonObj.get("string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("string").toString()));
       }
@@ -621,9 +622,9 @@ public class FormatTest implements Parcelable {
 
            @Override
            public FormatTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
index 9561a1988b1..74d8068918d 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
@@ -177,25 +177,26 @@ public class HasOnlyReadOnly implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to HasOnlyReadOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to HasOnlyReadOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!HasOnlyReadOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!HasOnlyReadOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in HasOnlyReadOnly is not found in the empty JSON string", HasOnlyReadOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!HasOnlyReadOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `HasOnlyReadOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `HasOnlyReadOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("bar") != null && !jsonObj.get("bar").isJsonNull()) && !jsonObj.get("bar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `bar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("bar").toString()));
       }
@@ -224,9 +225,9 @@ public class HasOnlyReadOnly implements Parcelable {
 
            @Override
            public HasOnlyReadOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/MapTest.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/MapTest.java
index 856c0102452..293e43e7a55 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/MapTest.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/MapTest.java
@@ -326,25 +326,26 @@ public class MapTest implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to MapTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to MapTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!MapTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!MapTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in MapTest is not found in the empty JSON string", MapTest.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!MapTest.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `MapTest` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `MapTest` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -367,9 +368,9 @@ public class MapTest implements Parcelable {
 
            @Override
            public MapTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
index c61faee6c1d..1f8ed3571ea 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
@@ -228,25 +228,26 @@ public class MixedPropertiesAndAdditionalPropertiesClass implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to MixedPropertiesAndAdditionalPropertiesClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to MixedPropertiesAndAdditionalPropertiesClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in MixedPropertiesAndAdditionalPropertiesClass is not found in the empty JSON string", MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!MixedPropertiesAndAdditionalPropertiesClass.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `MixedPropertiesAndAdditionalPropertiesClass` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `MixedPropertiesAndAdditionalPropertiesClass` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("uuid") != null && !jsonObj.get("uuid").isJsonNull()) && !jsonObj.get("uuid").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `uuid` to be a primitive type in the JSON string but got `%s`", jsonObj.get("uuid").toString()));
       }
@@ -272,9 +273,9 @@ public class MixedPropertiesAndAdditionalPropertiesClass implements Parcelable {
 
            @Override
            public MixedPropertiesAndAdditionalPropertiesClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Model200Response.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Model200Response.java
index 33d5b4bc6ae..34cdb74cec1 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Model200Response.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Model200Response.java
@@ -185,25 +185,26 @@ public class Model200Response implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Model200Response
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Model200Response
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Model200Response.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Model200Response.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Model200Response is not found in the empty JSON string", Model200Response.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Model200Response.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Model200Response` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Model200Response` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("class") != null && !jsonObj.get("class").isJsonNull()) && !jsonObj.get("class").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `class` to be a primitive type in the JSON string but got `%s`", jsonObj.get("class").toString()));
       }
@@ -229,9 +230,9 @@ public class Model200Response implements Parcelable {
 
            @Override
            public Model200Response read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelApiResponse.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelApiResponse.java
index d42917ddfbf..34415934711 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelApiResponse.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelApiResponse.java
@@ -215,25 +215,26 @@ public class ModelApiResponse implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelApiResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelApiResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelApiResponse is not found in the empty JSON string", ModelApiResponse.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ModelApiResponse.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelApiResponse` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelApiResponse` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -262,9 +263,9 @@ public class ModelApiResponse implements Parcelable {
 
            @Override
            public ModelApiResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelFile.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelFile.java
index fbcd27f9786..2a3a31856e0 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelFile.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelFile.java
@@ -155,25 +155,26 @@ public class ModelFile implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelFile
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelFile
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelFile.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelFile.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelFile is not found in the empty JSON string", ModelFile.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ModelFile.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelFile` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelFile` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("sourceURI") != null && !jsonObj.get("sourceURI").isJsonNull()) && !jsonObj.get("sourceURI").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `sourceURI` to be a primitive type in the JSON string but got `%s`", jsonObj.get("sourceURI").toString()));
       }
@@ -199,9 +200,9 @@ public class ModelFile implements Parcelable {
 
            @Override
            public ModelFile read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelList.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelList.java
index 8de2de772a6..e41d998cd53 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelList.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelList.java
@@ -155,25 +155,26 @@ public class ModelList implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelList
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelList
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelList.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelList.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelList is not found in the empty JSON string", ModelList.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ModelList.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelList` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelList` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("123-list") != null && !jsonObj.get("123-list").isJsonNull()) && !jsonObj.get("123-list").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `123-list` to be a primitive type in the JSON string but got `%s`", jsonObj.get("123-list").toString()));
       }
@@ -199,9 +200,9 @@ public class ModelList implements Parcelable {
 
            @Override
            public ModelList read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelReturn.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelReturn.java
index 64bd49cbebb..91566a2a416 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelReturn.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ModelReturn.java
@@ -155,25 +155,26 @@ public class ModelReturn implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelReturn
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelReturn
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelReturn.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelReturn.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelReturn is not found in the empty JSON string", ModelReturn.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ModelReturn.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelReturn` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ModelReturn` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -196,9 +197,9 @@ public class ModelReturn implements Parcelable {
 
            @Override
            public ModelReturn read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Name.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Name.java
index ee374135661..0377a5441fb 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Name.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Name.java
@@ -238,32 +238,33 @@ public class Name implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Name
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Name
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Name.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Name.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Name is not found in the empty JSON string", Name.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Name.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Name` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Name` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Name.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("property") != null && !jsonObj.get("property").isJsonNull()) && !jsonObj.get("property").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `property` to be a primitive type in the JSON string but got `%s`", jsonObj.get("property").toString()));
       }
@@ -289,9 +290,9 @@ public class Name implements Parcelable {
 
            @Override
            public Name read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/NumberOnly.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/NumberOnly.java
index 8ca528b97c0..649687b6871 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/NumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/NumberOnly.java
@@ -127,7 +127,7 @@ public class NumberOnly implements Parcelable {
   }
 
   NumberOnly(Parcel in) {
-    justNumber = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    justNumber = (BigDecimal)in.readValue(null);
   }
 
   public int describeContents() {
@@ -156,25 +156,26 @@ public class NumberOnly implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to NumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to NumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!NumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!NumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in NumberOnly is not found in the empty JSON string", NumberOnly.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!NumberOnly.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `NumberOnly` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `NumberOnly` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -197,9 +198,9 @@ public class NumberOnly implements Parcelable {
 
            @Override
            public NumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Order.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Order.java
index 6f7ea52c305..3e2af2fa86b 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Order.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Order.java
@@ -355,25 +355,26 @@ public class Order implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Order
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Order
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Order is not found in the empty JSON string", Order.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Order.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Order` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Order` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
       }
@@ -399,9 +400,9 @@ public class Order implements Parcelable {
 
            @Override
            public Order read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/OuterComposite.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/OuterComposite.java
index 89757730d0e..1852c987e61 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/OuterComposite.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/OuterComposite.java
@@ -183,7 +183,7 @@ public class OuterComposite implements Parcelable {
   }
 
   OuterComposite(Parcel in) {
-    myNumber = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    myNumber = (BigDecimal)in.readValue(null);
     myString = (String)in.readValue(null);
     myBoolean = (Boolean)in.readValue(null);
   }
@@ -216,25 +216,26 @@ public class OuterComposite implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to OuterComposite
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to OuterComposite
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!OuterComposite.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!OuterComposite.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in OuterComposite is not found in the empty JSON string", OuterComposite.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!OuterComposite.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `OuterComposite` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `OuterComposite` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("my_string") != null && !jsonObj.get("my_string").isJsonNull()) && !jsonObj.get("my_string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `my_string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("my_string").toString()));
       }
@@ -260,9 +261,9 @@ public class OuterComposite implements Parcelable {
 
            @Override
            public OuterComposite read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Pet.java
index 6cbe983ecea..e445c748eac 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Pet.java
@@ -378,35 +378,36 @@ public class Pet implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Pet.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Pet` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Pet` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -427,7 +428,7 @@ public class Pet implements Parcelable {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -456,9 +457,9 @@ public class Pet implements Parcelable {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
index ef44392cad9..b5b2eb7b65e 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
@@ -184,25 +184,26 @@ public class ReadOnlyFirst implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ReadOnlyFirst
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ReadOnlyFirst
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ReadOnlyFirst.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ReadOnlyFirst.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ReadOnlyFirst is not found in the empty JSON string", ReadOnlyFirst.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!ReadOnlyFirst.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ReadOnlyFirst` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `ReadOnlyFirst` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("bar") != null && !jsonObj.get("bar").isJsonNull()) && !jsonObj.get("bar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `bar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("bar").toString()));
       }
@@ -231,9 +232,9 @@ public class ReadOnlyFirst implements Parcelable {
 
            @Override
            public ReadOnlyFirst read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/SpecialModelName.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/SpecialModelName.java
index 444ff01b2d0..5ce5b2bc705 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/SpecialModelName.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/SpecialModelName.java
@@ -155,25 +155,26 @@ public class SpecialModelName implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to SpecialModelName
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to SpecialModelName
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!SpecialModelName.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!SpecialModelName.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in SpecialModelName is not found in the empty JSON string", SpecialModelName.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!SpecialModelName.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `SpecialModelName` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `SpecialModelName` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -196,9 +197,9 @@ public class SpecialModelName implements Parcelable {
 
            @Override
            public SpecialModelName read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Tag.java
index 682ab662d91..274d800bac2 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/Tag.java
@@ -185,25 +185,26 @@ public class Tag implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Tag.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Tag` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Tag` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -229,9 +230,9 @@ public class Tag implements Parcelable {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/TypeHolderDefault.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
index 3893c80bb0c..aa61005a3ab 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
@@ -250,7 +250,7 @@ public class TypeHolderDefault implements Parcelable {
 
   TypeHolderDefault(Parcel in) {
     stringItem = (String)in.readValue(null);
-    numberItem = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    numberItem = (BigDecimal)in.readValue(null);
     integerItem = (Integer)in.readValue(null);
     boolItem = (Boolean)in.readValue(null);
     arrayItem = (List<Integer>)in.readValue(null);
@@ -291,32 +291,33 @@ public class TypeHolderDefault implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to TypeHolderDefault
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to TypeHolderDefault
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!TypeHolderDefault.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!TypeHolderDefault.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in TypeHolderDefault is not found in the empty JSON string", TypeHolderDefault.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!TypeHolderDefault.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TypeHolderDefault` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TypeHolderDefault` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : TypeHolderDefault.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("string_item").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `string_item` to be a primitive type in the JSON string but got `%s`", jsonObj.get("string_item").toString()));
       }
@@ -348,9 +349,9 @@ public class TypeHolderDefault implements Parcelable {
 
            @Override
            public TypeHolderDefault read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/TypeHolderExample.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/TypeHolderExample.java
index c82c59beb67..625f3368ec0 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/TypeHolderExample.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/TypeHolderExample.java
@@ -278,7 +278,7 @@ public class TypeHolderExample implements Parcelable {
 
   TypeHolderExample(Parcel in) {
     stringItem = (String)in.readValue(null);
-    numberItem = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    numberItem = (BigDecimal)in.readValue(null);
     floatItem = (Float)in.readValue(null);
     integerItem = (Integer)in.readValue(null);
     boolItem = (Boolean)in.readValue(null);
@@ -322,32 +322,33 @@ public class TypeHolderExample implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to TypeHolderExample
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to TypeHolderExample
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!TypeHolderExample.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!TypeHolderExample.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in TypeHolderExample is not found in the empty JSON string", TypeHolderExample.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!TypeHolderExample.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TypeHolderExample` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `TypeHolderExample` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : TypeHolderExample.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("string_item").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `string_item` to be a primitive type in the JSON string but got `%s`", jsonObj.get("string_item").toString()));
       }
@@ -379,9 +380,9 @@ public class TypeHolderExample implements Parcelable {
 
            @Override
            public TypeHolderExample read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/User.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/User.java
index 26634053eda..c1badfd9fc6 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/User.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/User.java
@@ -365,25 +365,26 @@ public class User implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to User
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to User
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in User is not found in the empty JSON string", User.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!User.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `User` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `User` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("username") != null && !jsonObj.get("username").isJsonNull()) && !jsonObj.get("username").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `username` to be a primitive type in the JSON string but got `%s`", jsonObj.get("username").toString()));
       }
@@ -424,9 +425,9 @@ public class User implements Parcelable {
 
            @Override
            public User read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/XmlItem.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/XmlItem.java
index fe006213988..88767d327b4 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/XmlItem.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/model/XmlItem.java
@@ -986,30 +986,30 @@ public class XmlItem implements Parcelable {
 
   XmlItem(Parcel in) {
     attributeString = (String)in.readValue(null);
-    attributeNumber = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    attributeNumber = (BigDecimal)in.readValue(null);
     attributeInteger = (Integer)in.readValue(null);
     attributeBoolean = (Boolean)in.readValue(null);
     wrappedArray = (List<Integer>)in.readValue(null);
     nameString = (String)in.readValue(null);
-    nameNumber = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    nameNumber = (BigDecimal)in.readValue(null);
     nameInteger = (Integer)in.readValue(null);
     nameBoolean = (Boolean)in.readValue(null);
     nameArray = (List<Integer>)in.readValue(null);
     nameWrappedArray = (List<Integer>)in.readValue(null);
     prefixString = (String)in.readValue(null);
-    prefixNumber = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    prefixNumber = (BigDecimal)in.readValue(null);
     prefixInteger = (Integer)in.readValue(null);
     prefixBoolean = (Boolean)in.readValue(null);
     prefixArray = (List<Integer>)in.readValue(null);
     prefixWrappedArray = (List<Integer>)in.readValue(null);
     namespaceString = (String)in.readValue(null);
-    namespaceNumber = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    namespaceNumber = (BigDecimal)in.readValue(null);
     namespaceInteger = (Integer)in.readValue(null);
     namespaceBoolean = (Boolean)in.readValue(null);
     namespaceArray = (List<Integer>)in.readValue(null);
     namespaceWrappedArray = (List<Integer>)in.readValue(null);
     prefixNsString = (String)in.readValue(null);
-    prefixNsNumber = (BigDecimal)in.readValue(BigDecimal.class.getClassLoader());
+    prefixNsNumber = (BigDecimal)in.readValue(null);
     prefixNsInteger = (Integer)in.readValue(null);
     prefixNsBoolean = (Boolean)in.readValue(null);
     prefixNsArray = (List<Integer>)in.readValue(null);
@@ -1070,25 +1070,26 @@ public class XmlItem implements Parcelable {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to XmlItem
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to XmlItem
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!XmlItem.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!XmlItem.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in XmlItem is not found in the empty JSON string", XmlItem.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!XmlItem.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `XmlItem` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `XmlItem` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("attribute_string") != null && !jsonObj.get("attribute_string").isJsonNull()) && !jsonObj.get("attribute_string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `attribute_string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("attribute_string").toString()));
       }
@@ -1162,9 +1163,9 @@ public class XmlItem implements Parcelable {
 
            @Override
            public XmlItem read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Category.java b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Category.java
index a92cb8f181f..bb05d4b8e47 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Category.java
@@ -211,17 +211,18 @@ public class Category {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -264,8 +265,9 @@ public class Category {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Category instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/ModelApiResponse.java b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/ModelApiResponse.java
index 8dfc9b86ef0..8eae862a66d 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/ModelApiResponse.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/ModelApiResponse.java
@@ -240,17 +240,18 @@ public class ModelApiResponse {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelApiResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelApiResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelApiResponse is not found in the empty JSON string", ModelApiResponse.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -296,8 +297,9 @@ public class ModelApiResponse {
 
            @Override
            public ModelApiResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelApiResponse instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Order.java b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Order.java
index a1884aec7e1..487981d5a7e 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Order.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Order.java
@@ -377,17 +377,18 @@ public class Order {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Order
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Order
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Order is not found in the empty JSON string", Order.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
       }
@@ -430,8 +431,9 @@ public class Order {
 
            @Override
            public Order read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Order instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Pet.java
index ee97623c9ef..eaf6164bdd9 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Pet.java
@@ -403,27 +403,28 @@ public class Pet {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -444,7 +445,7 @@ public class Pet {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -490,8 +491,9 @@ public class Pet {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Pet instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Tag.java
index 0ddcdf0e439..f085f281660 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/Tag.java
@@ -211,17 +211,18 @@ public class Tag {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -264,8 +265,9 @@ public class Tag {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Tag instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/User.java b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/User.java
index b4bbf80f7f7..c814e79ab76 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/User.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/model/User.java
@@ -385,17 +385,18 @@ public class User {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to User
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to User
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in User is not found in the empty JSON string", User.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("username") != null && !jsonObj.get("username").isJsonNull()) && !jsonObj.get("username").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `username` to be a primitive type in the JSON string but got `%s`", jsonObj.get("username").toString()));
       }
@@ -453,8 +454,9 @@ public class User {
 
            @Override
            public User read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              User instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Category.java b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Category.java
index 394267123e7..c41e7dc2d0d 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Category.java
@@ -210,17 +210,18 @@ public class Category {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -263,8 +264,9 @@ public class Category {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Category instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/ModelApiResponse.java b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/ModelApiResponse.java
index addf4013a3b..fce61eba0bd 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/ModelApiResponse.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/ModelApiResponse.java
@@ -239,17 +239,18 @@ public class ModelApiResponse {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelApiResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelApiResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelApiResponse is not found in the empty JSON string", ModelApiResponse.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -295,8 +296,9 @@ public class ModelApiResponse {
 
            @Override
            public ModelApiResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelApiResponse instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Order.java b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Order.java
index 915cc2ee4b5..6448a5ad9cc 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Order.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Order.java
@@ -376,17 +376,18 @@ public class Order {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Order
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Order
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Order is not found in the empty JSON string", Order.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
       }
@@ -429,8 +430,9 @@ public class Order {
 
            @Override
            public Order read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Order instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Pet.java
index 970423721ec..4d1a3ad69ae 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Pet.java
@@ -402,27 +402,28 @@ public class Pet {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -443,7 +444,7 @@ public class Pet {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -489,8 +490,9 @@ public class Pet {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Pet instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Tag.java
index 785c66cb3c5..d2fca801664 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/Tag.java
@@ -210,17 +210,18 @@ public class Tag {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -263,8 +264,9 @@ public class Tag {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Tag instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/User.java b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/User.java
index 2def290eca1..bd9d4f6ea7f 100644
--- a/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/User.java
+++ b/samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/model/User.java
@@ -384,17 +384,18 @@ public class User {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to User
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to User
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in User is not found in the empty JSON string", User.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("username") != null && !jsonObj.get("username").isJsonNull()) && !jsonObj.get("username").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `username` to be a primitive type in the JSON string but got `%s`", jsonObj.get("username").toString()));
       }
@@ -452,8 +453,9 @@ public class User {
 
            @Override
            public User read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              User instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/.openapi-generator/FILES b/samples/client/petstore/java/okhttp-gson/.openapi-generator/FILES
index 5382db19ae8..1f3688156d9 100644
--- a/samples/client/petstore/java/okhttp-gson/.openapi-generator/FILES
+++ b/samples/client/petstore/java/okhttp-gson/.openapi-generator/FILES
@@ -75,6 +75,7 @@ docs/Pig.md
 docs/Quadrilateral.md
 docs/QuadrilateralInterface.md
 docs/ReadOnlyFirst.md
+docs/Scalar.md
 docs/ScaleneTriangle.md
 docs/Shape.md
 docs/ShapeInterface.md
@@ -87,6 +88,9 @@ docs/Triangle.md
 docs/TriangleInterface.md
 docs/User.md
 docs/UserApi.md
+docs/Value.md
+docs/ValuesApi.md
+docs/Variable.md
 docs/Whale.md
 docs/Zebra.md
 git_push.sh
@@ -118,6 +122,7 @@ src/main/java/org/openapitools/client/api/FakeClassnameTags123Api.java
 src/main/java/org/openapitools/client/api/PetApi.java
 src/main/java/org/openapitools/client/api/StoreApi.java
 src/main/java/org/openapitools/client/api/UserApi.java
+src/main/java/org/openapitools/client/api/ValuesApi.java
 src/main/java/org/openapitools/client/auth/ApiKeyAuth.java
 src/main/java/org/openapitools/client/auth/Authentication.java
 src/main/java/org/openapitools/client/auth/HttpBasicAuth.java
@@ -192,6 +197,7 @@ src/main/java/org/openapitools/client/model/Pig.java
 src/main/java/org/openapitools/client/model/Quadrilateral.java
 src/main/java/org/openapitools/client/model/QuadrilateralInterface.java
 src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
+src/main/java/org/openapitools/client/model/Scalar.java
 src/main/java/org/openapitools/client/model/ScaleneTriangle.java
 src/main/java/org/openapitools/client/model/Shape.java
 src/main/java/org/openapitools/client/model/ShapeInterface.java
@@ -202,5 +208,7 @@ src/main/java/org/openapitools/client/model/Tag.java
 src/main/java/org/openapitools/client/model/Triangle.java
 src/main/java/org/openapitools/client/model/TriangleInterface.java
 src/main/java/org/openapitools/client/model/User.java
+src/main/java/org/openapitools/client/model/Value.java
+src/main/java/org/openapitools/client/model/Variable.java
 src/main/java/org/openapitools/client/model/Whale.java
 src/main/java/org/openapitools/client/model/Zebra.java
diff --git a/samples/client/petstore/java/okhttp-gson/README.md b/samples/client/petstore/java/okhttp-gson/README.md
index c6e92043eb7..aa3d3f8a76a 100644
--- a/samples/client/petstore/java/okhttp-gson/README.md
+++ b/samples/client/petstore/java/okhttp-gson/README.md
@@ -152,6 +152,7 @@ Class | Method | HTTP request | Description
 *UserApi* | [**loginUser**](docs/UserApi.md#loginUser) | **GET** /user/login | Logs user into the system
 *UserApi* | [**logoutUser**](docs/UserApi.md#logoutUser) | **GET** /user/logout | Logs out current logged in user session
 *UserApi* | [**updateUser**](docs/UserApi.md#updateUser) | **PUT** /user/{username} | Updated user
+*ValuesApi* | [**getSomeValues**](docs/ValuesApi.md#getSomeValues) | **GET** /values | Get some primitive variable values
 
 
 ## Documentation for Models
@@ -221,6 +222,7 @@ Class | Method | HTTP request | Description
  - [Quadrilateral](docs/Quadrilateral.md)
  - [QuadrilateralInterface](docs/QuadrilateralInterface.md)
  - [ReadOnlyFirst](docs/ReadOnlyFirst.md)
+ - [Scalar](docs/Scalar.md)
  - [ScaleneTriangle](docs/ScaleneTriangle.md)
  - [Shape](docs/Shape.md)
  - [ShapeInterface](docs/ShapeInterface.md)
@@ -231,6 +233,8 @@ Class | Method | HTTP request | Description
  - [Triangle](docs/Triangle.md)
  - [TriangleInterface](docs/TriangleInterface.md)
  - [User](docs/User.md)
+ - [Value](docs/Value.md)
+ - [Variable](docs/Variable.md)
  - [Whale](docs/Whale.md)
  - [Zebra](docs/Zebra.md)
 
diff --git a/samples/client/petstore/java/okhttp-gson/api/openapi.yaml b/samples/client/petstore/java/okhttp-gson/api/openapi.yaml
index 37d63448ada..cbd2a9762e9 100644
--- a/samples/client/petstore/java/okhttp-gson/api/openapi.yaml
+++ b/samples/client/petstore/java/okhttp-gson/api/openapi.yaml
@@ -1132,6 +1132,23 @@ paths:
       tags:
       - fake
       x-accepts: application/json
+  /values:
+    get:
+      description: ""
+      operationId: getSomeValues
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Variable'
+          description: successful operation
+        "400":
+          description: Invalid Value
+      summary: Get some primitive variable values
+      tags:
+      - values
+      x-accepts: application/json
 components:
   requestBodies:
     UserArray:
@@ -2217,6 +2234,37 @@ components:
           items:
             type: string
           type: array
+    Variable:
+      description: Value object
+      example:
+        name: variable_1
+        value: null
+      properties:
+        name:
+          example: variable_1
+          type: string
+        value:
+          $ref: '#/components/schemas/Value'
+      required:
+      - name
+      - value
+    Value:
+      oneOf:
+      - $ref: '#/components/schemas/Scalar'
+      - $ref: '#/components/schemas/Array'
+    Scalar:
+      description: Values of scalar type
+      oneOf:
+      - maxLength: 1089
+        type: string
+      - type: number
+      - type: boolean
+    Array:
+      description: Values of array type
+      items:
+        $ref: '#/components/schemas/Scalar'
+      minItems: 1
+      type: array
     _foo_get_default_response:
       example:
         string:
diff --git a/samples/client/petstore/java/okhttp-gson/docs/FakeApi.md b/samples/client/petstore/java/okhttp-gson/docs/FakeApi.md
index 31173ac52df..fbda6fca391 100644
--- a/samples/client/petstore/java/okhttp-gson/docs/FakeApi.md
+++ b/samples/client/petstore/java/okhttp-gson/docs/FakeApi.md
@@ -247,7 +247,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/okhttp-gson/docs/Scalar.md b/samples/client/petstore/java/okhttp-gson/docs/Scalar.md
new file mode 100644
index 00000000000..45dbf799e91
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/docs/Scalar.md
@@ -0,0 +1,13 @@
+
+
+# Scalar
+
+Values of scalar type
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+
+
+
diff --git a/samples/client/petstore/java/okhttp-gson/docs/Value.md b/samples/client/petstore/java/okhttp-gson/docs/Value.md
new file mode 100644
index 00000000000..54c8fc245e7
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/docs/Value.md
@@ -0,0 +1,12 @@
+
+
+# Value
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+
+
+
diff --git a/samples/client/petstore/java/okhttp-gson/docs/ValuesApi.md b/samples/client/petstore/java/okhttp-gson/docs/ValuesApi.md
new file mode 100644
index 00000000000..4210bff03ec
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/docs/ValuesApi.md
@@ -0,0 +1,68 @@
+# ValuesApi
+
+All URIs are relative to *http://petstore.swagger.io:80/v2*
+
+| Method | HTTP request | Description |
+|------------- | ------------- | -------------|
+| [**getSomeValues**](ValuesApi.md#getSomeValues) | **GET** /values | Get some primitive variable values |
+
+
+<a id="getSomeValues"></a>
+# **getSomeValues**
+> Variable getSomeValues()
+
+Get some primitive variable values
+
+
+
+### Example
+```java
+// Import classes:
+import org.openapitools.client.ApiClient;
+import org.openapitools.client.ApiException;
+import org.openapitools.client.Configuration;
+import org.openapitools.client.models.*;
+import org.openapitools.client.api.ValuesApi;
+
+public class Example {
+  public static void main(String[] args) {
+    ApiClient defaultClient = Configuration.getDefaultApiClient();
+    defaultClient.setBasePath("http://petstore.swagger.io:80/v2");
+
+    ValuesApi apiInstance = new ValuesApi(defaultClient);
+    try {
+      Variable result = apiInstance.getSomeValues();
+      System.out.println(result);
+    } catch (ApiException e) {
+      System.err.println("Exception when calling ValuesApi#getSomeValues");
+      System.err.println("Status code: " + e.getCode());
+      System.err.println("Reason: " + e.getResponseBody());
+      System.err.println("Response headers: " + e.getResponseHeaders());
+      e.printStackTrace();
+    }
+  }
+}
+```
+
+### Parameters
+This endpoint does not need any parameter.
+
+### Return type
+
+[**Variable**](Variable.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/json
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+| **400** | Invalid Value |  -  |
+
diff --git a/samples/client/petstore/java/okhttp-gson/docs/Variable.md b/samples/client/petstore/java/okhttp-gson/docs/Variable.md
new file mode 100644
index 00000000000..d179fb1775c
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/docs/Variable.md
@@ -0,0 +1,15 @@
+
+
+# Variable
+
+Value object
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**name** | **String** |  |  |
+|**value** | [**Value**](Value.md) |  |  |
+
+
+
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
index 8f3da91a013..fe260c5f9eb 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java
@@ -287,6 +287,7 @@ public class JSON {
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Quadrilateral.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.QuadrilateralInterface.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.ReadOnlyFirst.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Scalar.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.ScaleneTriangle.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Shape.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.ShapeInterface.CustomTypeAdapterFactory());
@@ -297,6 +298,8 @@ public class JSON {
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Triangle.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.TriangleInterface.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.User.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Value.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Variable.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Whale.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Zebra.CustomTypeAdapterFactory());
         gson = gsonBuilder.create();
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/api/ValuesApi.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/api/ValuesApi.java
new file mode 100644
index 00000000000..79fe043970d
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/api/ValuesApi.java
@@ -0,0 +1,192 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.api;
+
+import org.openapitools.client.ApiCallback;
+import org.openapitools.client.ApiClient;
+import org.openapitools.client.ApiException;
+import org.openapitools.client.ApiResponse;
+import org.openapitools.client.Configuration;
+import org.openapitools.client.Pair;
+import org.openapitools.client.ProgressRequestBody;
+import org.openapitools.client.ProgressResponseBody;
+
+import com.google.gson.reflect.TypeToken;
+
+import java.io.IOException;
+
+
+import org.openapitools.client.model.Variable;
+
+import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class ValuesApi {
+    private ApiClient localVarApiClient;
+    private int localHostIndex;
+    private String localCustomBaseUrl;
+
+    public ValuesApi() {
+        this(Configuration.getDefaultApiClient());
+    }
+
+    public ValuesApi(ApiClient apiClient) {
+        this.localVarApiClient = apiClient;
+    }
+
+    public ApiClient getApiClient() {
+        return localVarApiClient;
+    }
+
+    public void setApiClient(ApiClient apiClient) {
+        this.localVarApiClient = apiClient;
+    }
+
+    public int getHostIndex() {
+        return localHostIndex;
+    }
+
+    public void setHostIndex(int hostIndex) {
+        this.localHostIndex = hostIndex;
+    }
+
+    public String getCustomBaseUrl() {
+        return localCustomBaseUrl;
+    }
+
+    public void setCustomBaseUrl(String customBaseUrl) {
+        this.localCustomBaseUrl = customBaseUrl;
+    }
+
+    /**
+     * Build call for getSomeValues
+     * @param _callback Callback for upload/download progress
+     * @return Call to execute
+     * @throws ApiException If fail to serialize the request body object
+     * @http.response.details
+     <table summary="Response Details" border="1">
+        <tr><td> Status Code </td><td> Description </td><td> Response Headers </td></tr>
+        <tr><td> 200 </td><td> successful operation </td><td>  -  </td></tr>
+        <tr><td> 400 </td><td> Invalid Value </td><td>  -  </td></tr>
+     </table>
+     */
+    public okhttp3.Call getSomeValuesCall(final ApiCallback _callback) throws ApiException {
+        String basePath = null;
+        // Operation Servers
+        String[] localBasePaths = new String[] {  };
+
+        // Determine Base Path to Use
+        if (localCustomBaseUrl != null){
+            basePath = localCustomBaseUrl;
+        } else if ( localBasePaths.length > 0 ) {
+            basePath = localBasePaths[localHostIndex];
+        } else {
+            basePath = null;
+        }
+
+        Object localVarPostBody = null;
+
+        // create path and map variables
+        String localVarPath = "/values";
+
+        List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
+        Map<String, String> localVarHeaderParams = new HashMap<String, String>();
+        Map<String, String> localVarCookieParams = new HashMap<String, String>();
+        Map<String, Object> localVarFormParams = new HashMap<String, Object>();
+
+        final String[] localVarAccepts = {
+            "application/json"
+        };
+        final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
+        if (localVarAccept != null) {
+            localVarHeaderParams.put("Accept", localVarAccept);
+        }
+
+        final String[] localVarContentTypes = {
+        };
+        final String localVarContentType = localVarApiClient.selectHeaderContentType(localVarContentTypes);
+        if (localVarContentType != null) {
+            localVarHeaderParams.put("Content-Type", localVarContentType);
+        }
+
+        String[] localVarAuthNames = new String[] {  };
+        return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
+    }
+
+    @SuppressWarnings("rawtypes")
+    private okhttp3.Call getSomeValuesValidateBeforeCall(final ApiCallback _callback) throws ApiException {
+        return getSomeValuesCall(_callback);
+
+    }
+
+    /**
+     * Get some primitive variable values
+     * 
+     * @return Variable
+     * @throws ApiException If fail to call the API, e.g. server error or cannot deserialize the response body
+     * @http.response.details
+     <table summary="Response Details" border="1">
+        <tr><td> Status Code </td><td> Description </td><td> Response Headers </td></tr>
+        <tr><td> 200 </td><td> successful operation </td><td>  -  </td></tr>
+        <tr><td> 400 </td><td> Invalid Value </td><td>  -  </td></tr>
+     </table>
+     */
+    public Variable getSomeValues() throws ApiException {
+        ApiResponse<Variable> localVarResp = getSomeValuesWithHttpInfo();
+        return localVarResp.getData();
+    }
+
+    /**
+     * Get some primitive variable values
+     * 
+     * @return ApiResponse&lt;Variable&gt;
+     * @throws ApiException If fail to call the API, e.g. server error or cannot deserialize the response body
+     * @http.response.details
+     <table summary="Response Details" border="1">
+        <tr><td> Status Code </td><td> Description </td><td> Response Headers </td></tr>
+        <tr><td> 200 </td><td> successful operation </td><td>  -  </td></tr>
+        <tr><td> 400 </td><td> Invalid Value </td><td>  -  </td></tr>
+     </table>
+     */
+    public ApiResponse<Variable> getSomeValuesWithHttpInfo() throws ApiException {
+        okhttp3.Call localVarCall = getSomeValuesValidateBeforeCall(null);
+        Type localVarReturnType = new TypeToken<Variable>(){}.getType();
+        return localVarApiClient.execute(localVarCall, localVarReturnType);
+    }
+
+    /**
+     * Get some primitive variable values (asynchronously)
+     * 
+     * @param _callback The callback to be executed when the API call finishes
+     * @return The request call
+     * @throws ApiException If fail to process the API call, e.g. serializing the request body object
+     * @http.response.details
+     <table summary="Response Details" border="1">
+        <tr><td> Status Code </td><td> Description </td><td> Response Headers </td></tr>
+        <tr><td> 200 </td><td> successful operation </td><td>  -  </td></tr>
+        <tr><td> 400 </td><td> Invalid Value </td><td>  -  </td></tr>
+     </table>
+     */
+    public okhttp3.Call getSomeValuesAsync(final ApiCallback<Variable> _callback) throws ApiException {
+
+        okhttp3.Call localVarCall = getSomeValuesValidateBeforeCall(_callback);
+        Type localVarReturnType = new TypeToken<Variable>(){}.getType();
+        localVarApiClient.executeAsync(localVarCall, localVarReturnType, _callback);
+        return localVarCall;
+    }
+}
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
index 74c49465a2b..e5a878d231b 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
@@ -420,17 +420,18 @@ public class AdditionalPropertiesClass {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AdditionalPropertiesClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AdditionalPropertiesClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AdditionalPropertiesClass is not found in the empty JSON string", AdditionalPropertiesClass.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -470,8 +471,9 @@ public class AdditionalPropertiesClass {
 
            @Override
            public AdditionalPropertiesClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              AdditionalPropertiesClass instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Animal.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Animal.java
index 456a014ad16..e58ec854497 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Animal.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Animal.java
@@ -208,25 +208,25 @@ public class Animal {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Animal
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Animal
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Animal.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Animal.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Animal is not found in the empty JSON string", Animal.openapiRequiredFields.toString()));
         }
       }
 
-      String discriminatorValue = jsonObj.get("className").getAsString();
+      String discriminatorValue = jsonElement.getAsJsonObject().get("className").getAsString();
       switch (discriminatorValue) {
         case "Cat":
-          Cat.validateJsonObject(jsonObj);
+          Cat.validateJsonElement(jsonElement);
           break;
         case "Dog":
-          Dog.validateJsonObject(jsonObj);
+          Dog.validateJsonElement(jsonElement);
           break;
         default:
           throw new IllegalArgumentException(String.format("The value of the `className` field `%s` does not match any key defined in the discriminator's mapping.", discriminatorValue));
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Apple.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Apple.java
index f79aee0b096..ec73aad5cff 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Apple.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Apple.java
@@ -206,17 +206,18 @@ public class Apple {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Apple
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Apple
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Apple.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Apple.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Apple is not found in the empty JSON string", Apple.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("cultivar") != null && !jsonObj.get("cultivar").isJsonNull()) && !jsonObj.get("cultivar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `cultivar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("cultivar").toString()));
       }
@@ -262,8 +263,9 @@ public class Apple {
 
            @Override
            public Apple read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Apple instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/AppleReq.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/AppleReq.java
index 008bac90d68..9c06337931d 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/AppleReq.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/AppleReq.java
@@ -161,32 +161,33 @@ public class AppleReq {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to AppleReq
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to AppleReq
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!AppleReq.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!AppleReq.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in AppleReq is not found in the empty JSON string", AppleReq.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!AppleReq.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AppleReq` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `AppleReq` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : AppleReq.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("cultivar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `cultivar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("cultivar").toString()));
       }
@@ -212,9 +213,9 @@ public class AppleReq {
 
            @Override
            public AppleReq read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayDefault.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayDefault.java
index faf0066b0d3..8c7e032210c 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayDefault.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayDefault.java
@@ -224,17 +224,18 @@ public class ArrayDefault {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayDefault
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayDefault
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayDefault.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayDefault.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayDefault is not found in the empty JSON string", ArrayDefault.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("WithDefaultEmptyBracket") != null && !jsonObj.get("WithDefaultEmptyBracket").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `WithDefaultEmptyBracket` to be an array in the JSON string but got `%s`", jsonObj.get("WithDefaultEmptyBracket").toString()));
@@ -282,8 +283,9 @@ public class ArrayDefault {
 
            @Override
            public ArrayDefault read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ArrayDefault instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
index 72221326b8f..6a0757332fa 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfArrayOfNumberOnly.java
@@ -189,17 +189,18 @@ public class ArrayOfArrayOfNumberOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfArrayOfNumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfArrayOfNumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfArrayOfNumberOnly is not found in the empty JSON string", ArrayOfArrayOfNumberOnly.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("ArrayArrayNumber") != null && !jsonObj.get("ArrayArrayNumber").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `ArrayArrayNumber` to be an array in the JSON string but got `%s`", jsonObj.get("ArrayArrayNumber").toString()));
@@ -243,8 +244,9 @@ public class ArrayOfArrayOfNumberOnly {
 
            @Override
            public ArrayOfArrayOfNumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ArrayOfArrayOfNumberOnly instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOf.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOf.java
index f22fd8bad10..3ea11559534 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOf.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOf.java
@@ -246,24 +246,25 @@ public class ArrayOfInlineAllOf {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfInlineAllOf
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfInlineAllOf
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfInlineAllOf.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfInlineAllOf.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfInlineAllOf is not found in the empty JSON string", ArrayOfInlineAllOf.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : ArrayOfInlineAllOf.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -277,7 +278,7 @@ public class ArrayOfInlineAllOf {
 
           // validate the optional field `array_allof_dog_property` (array)
           for (int i = 0; i < jsonArrayarrayAllofDogProperty.size(); i++) {
-            ArrayOfInlineAllOfArrayAllofDogPropertyInner.validateJsonObject(jsonArrayarrayAllofDogProperty.get(i).getAsJsonObject());
+            ArrayOfInlineAllOfArrayAllofDogPropertyInner.validateJsonElement(jsonArrayarrayAllofDogProperty.get(i));
           };
         }
       }
@@ -320,8 +321,9 @@ public class ArrayOfInlineAllOf {
 
            @Override
            public ArrayOfInlineAllOf read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ArrayOfInlineAllOf instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOfArrayAllofDogPropertyInner.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOfArrayAllofDogPropertyInner.java
index 4ae849ab5c9..91c027c30c9 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOfArrayAllofDogPropertyInner.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOfArrayAllofDogPropertyInner.java
@@ -206,17 +206,18 @@ public class ArrayOfInlineAllOfArrayAllofDogPropertyInner {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfInlineAllOfArrayAllofDogPropertyInner
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfInlineAllOfArrayAllofDogPropertyInner
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfInlineAllOfArrayAllofDogPropertyInner.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfInlineAllOfArrayAllofDogPropertyInner.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfInlineAllOfArrayAllofDogPropertyInner is not found in the empty JSON string", ArrayOfInlineAllOfArrayAllofDogPropertyInner.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("breed") != null && !jsonObj.get("breed").isJsonNull()) && !jsonObj.get("breed").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `breed` to be a primitive type in the JSON string but got `%s`", jsonObj.get("breed").toString()));
       }
@@ -262,8 +263,9 @@ public class ArrayOfInlineAllOfArrayAllofDogPropertyInner {
 
            @Override
            public ArrayOfInlineAllOfArrayAllofDogPropertyInner read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ArrayOfInlineAllOfArrayAllofDogPropertyInner instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1.java
index 98c23a298d8..bc3f44944dc 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1.java
@@ -178,17 +178,18 @@ public class ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1 {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1 is not found in the empty JSON string", ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("color") != null && !jsonObj.get("color").isJsonNull()) && !jsonObj.get("color").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `color` to be a primitive type in the JSON string but got `%s`", jsonObj.get("color").toString()));
       }
@@ -231,8 +232,9 @@ public class ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1 {
 
            @Override
            public ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1 read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ArrayOfInlineAllOfArrayAllofDogPropertyInnerAllOf1 instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index 72b5d022389..e5eba3faa81 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -189,17 +189,18 @@ public class ArrayOfNumberOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayOfNumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayOfNumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfNumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfNumberOnly is not found in the empty JSON string", ArrayOfNumberOnly.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("ArrayNumber") != null && !jsonObj.get("ArrayNumber").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `ArrayNumber` to be an array in the JSON string but got `%s`", jsonObj.get("ArrayNumber").toString()));
@@ -243,8 +244,9 @@ public class ArrayOfNumberOnly {
 
            @Override
            public ArrayOfNumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ArrayOfNumberOnly instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayTest.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayTest.java
index 71d6444e42a..91ec8e7760a 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayTest.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ArrayTest.java
@@ -261,17 +261,18 @@ public class ArrayTest {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ArrayTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ArrayTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ArrayTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayTest is not found in the empty JSON string", ArrayTest.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // ensure the optional json data is an array if present
       if (jsonObj.get("array_of_string") != null && !jsonObj.get("array_of_string").isJsonArray()) {
         throw new IllegalArgumentException(String.format("Expected the field `array_of_string` to be an array in the JSON string but got `%s`", jsonObj.get("array_of_string").toString()));
@@ -323,8 +324,9 @@ public class ArrayTest {
 
            @Override
            public ArrayTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ArrayTest instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Banana.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Banana.java
index 07cf43f0b23..77c4a98340a 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Banana.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Banana.java
@@ -179,17 +179,18 @@ public class Banana {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Banana
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Banana
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Banana.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Banana.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Banana is not found in the empty JSON string", Banana.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -229,8 +230,9 @@ public class Banana {
 
            @Override
            public Banana read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Banana instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BananaReq.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BananaReq.java
index 5a5873b4ff0..aa374a9eaee 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BananaReq.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BananaReq.java
@@ -162,32 +162,33 @@ public class BananaReq {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to BananaReq
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to BananaReq
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!BananaReq.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!BananaReq.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in BananaReq is not found in the empty JSON string", BananaReq.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!BananaReq.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `BananaReq` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `BananaReq` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : BananaReq.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -210,9 +211,9 @@ public class BananaReq {
 
            @Override
            public BananaReq read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BasquePig.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BasquePig.java
index 82ec8157770..44b15d582a9 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BasquePig.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BasquePig.java
@@ -179,24 +179,25 @@ public class BasquePig {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to BasquePig
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to BasquePig
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!BasquePig.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!BasquePig.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in BasquePig is not found in the empty JSON string", BasquePig.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : BasquePig.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("className").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `className` to be a primitive type in the JSON string but got `%s`", jsonObj.get("className").toString()));
       }
@@ -239,8 +240,9 @@ public class BasquePig {
 
            @Override
            public BasquePig read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              BasquePig instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Capitalization.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Capitalization.java
index 31807cf8ad1..3e5e5c3bcc5 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Capitalization.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Capitalization.java
@@ -318,17 +318,18 @@ public class Capitalization {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Capitalization
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Capitalization
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Capitalization.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Capitalization.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Capitalization is not found in the empty JSON string", Capitalization.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("smallCamel") != null && !jsonObj.get("smallCamel").isJsonNull()) && !jsonObj.get("smallCamel").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `smallCamel` to be a primitive type in the JSON string but got `%s`", jsonObj.get("smallCamel").toString()));
       }
@@ -386,8 +387,9 @@ public class Capitalization {
 
            @Override
            public Capitalization read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Capitalization instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Cat.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Cat.java
index f86bb2e5c4b..f96aed7c712 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Cat.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Cat.java
@@ -185,22 +185,22 @@ public class Cat extends Animal {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Cat
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Cat
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Cat.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Cat.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Cat is not found in the empty JSON string", Cat.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Cat.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
   }
@@ -242,8 +242,9 @@ public class Cat extends Animal {
 
            @Override
            public Cat read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Cat instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Category.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Category.java
index af4a957bc64..ff4a2baa136 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Category.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Category.java
@@ -207,24 +207,25 @@ public class Category {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Category
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Category
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Category.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Category is not found in the empty JSON string", Category.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Category.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -267,8 +268,9 @@ public class Category {
 
            @Override
            public Category read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Category instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ClassModel.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ClassModel.java
index 8997a5d56a5..ebe9b92a01e 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ClassModel.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ClassModel.java
@@ -178,17 +178,18 @@ public class ClassModel {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ClassModel
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ClassModel
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ClassModel.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ClassModel.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ClassModel is not found in the empty JSON string", ClassModel.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("_class") != null && !jsonObj.get("_class").isJsonNull()) && !jsonObj.get("_class").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `_class` to be a primitive type in the JSON string but got `%s`", jsonObj.get("_class").toString()));
       }
@@ -231,8 +232,9 @@ public class ClassModel {
 
            @Override
            public ClassModel read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ClassModel instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Client.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Client.java
index fc94d1e4534..889269ad74d 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Client.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Client.java
@@ -178,17 +178,18 @@ public class Client {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Client
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Client
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Client.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Client.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Client is not found in the empty JSON string", Client.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("client") != null && !jsonObj.get("client").isJsonNull()) && !jsonObj.get("client").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `client` to be a primitive type in the JSON string but got `%s`", jsonObj.get("client").toString()));
       }
@@ -231,8 +232,9 @@ public class Client {
 
            @Override
            public Client read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Client instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ComplexQuadrilateral.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ComplexQuadrilateral.java
index b922c61c8ea..1423b3e35ed 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ComplexQuadrilateral.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ComplexQuadrilateral.java
@@ -208,24 +208,25 @@ public class ComplexQuadrilateral {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ComplexQuadrilateral
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ComplexQuadrilateral
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ComplexQuadrilateral.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ComplexQuadrilateral.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ComplexQuadrilateral is not found in the empty JSON string", ComplexQuadrilateral.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : ComplexQuadrilateral.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("shapeType").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `shapeType` to be a primitive type in the JSON string but got `%s`", jsonObj.get("shapeType").toString()));
       }
@@ -271,8 +272,9 @@ public class ComplexQuadrilateral {
 
            @Override
            public ComplexQuadrilateral read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ComplexQuadrilateral instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/DanishPig.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/DanishPig.java
index 8898cb96ebd..ac41d9e33f1 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/DanishPig.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/DanishPig.java
@@ -179,24 +179,25 @@ public class DanishPig {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to DanishPig
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to DanishPig
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!DanishPig.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!DanishPig.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in DanishPig is not found in the empty JSON string", DanishPig.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : DanishPig.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("className").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `className` to be a primitive type in the JSON string but got `%s`", jsonObj.get("className").toString()));
       }
@@ -239,8 +240,9 @@ public class DanishPig {
 
            @Override
            public DanishPig read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              DanishPig instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/DeprecatedObject.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/DeprecatedObject.java
index 59ec0749515..de730d31bb6 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/DeprecatedObject.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/DeprecatedObject.java
@@ -180,17 +180,18 @@ public class DeprecatedObject {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to DeprecatedObject
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to DeprecatedObject
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!DeprecatedObject.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!DeprecatedObject.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in DeprecatedObject is not found in the empty JSON string", DeprecatedObject.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -233,8 +234,9 @@ public class DeprecatedObject {
 
            @Override
            public DeprecatedObject read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              DeprecatedObject instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Dog.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Dog.java
index c4573657dc9..57c17459cf2 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Dog.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Dog.java
@@ -185,22 +185,22 @@ public class Dog extends Animal {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Dog
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Dog
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Dog.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Dog.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Dog is not found in the empty JSON string", Dog.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Dog.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
   }
@@ -242,8 +242,9 @@ public class Dog extends Animal {
 
            @Override
            public Dog read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Dog instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Drawing.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Drawing.java
index 1a9f8e1a90e..ea738037f86 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Drawing.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Drawing.java
@@ -242,36 +242,37 @@ public class Drawing {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Drawing
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Drawing
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Drawing.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Drawing.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Drawing is not found in the empty JSON string", Drawing.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!Drawing.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Drawing` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `Drawing` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `mainShape`
       if (jsonObj.get("mainShape") != null && !jsonObj.get("mainShape").isJsonNull()) {
-        Shape.validateJsonObject(jsonObj.getAsJsonObject("mainShape"));
+        Shape.validateJsonElement(jsonObj.get("mainShape"));
       }
       // validate the optional field `shapeOrNull`
       if (jsonObj.get("shapeOrNull") != null && !jsonObj.get("shapeOrNull").isJsonNull()) {
-        ShapeOrNull.validateJsonObject(jsonObj.getAsJsonObject("shapeOrNull"));
+        ShapeOrNull.validateJsonElement(jsonObj.get("shapeOrNull"));
       }
       // validate the optional field `nullableShape`
       if (jsonObj.get("nullableShape") != null && !jsonObj.get("nullableShape").isJsonNull()) {
-        NullableShape.validateJsonObject(jsonObj.getAsJsonObject("nullableShape"));
+        NullableShape.validateJsonElement(jsonObj.get("nullableShape"));
       }
       if (jsonObj.get("shapes") != null && !jsonObj.get("shapes").isJsonNull()) {
         JsonArray jsonArrayshapes = jsonObj.getAsJsonArray("shapes");
@@ -283,7 +284,7 @@ public class Drawing {
 
           // validate the optional field `shapes` (array)
           for (int i = 0; i < jsonArrayshapes.size(); i++) {
-            Shape.validateJsonObject(jsonArrayshapes.get(i).getAsJsonObject());
+            Shape.validateJsonElement(jsonArrayshapes.get(i));
           };
         }
       }
@@ -309,9 +310,9 @@ public class Drawing {
 
            @Override
            public Drawing read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumArrays.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumArrays.java
index fbb08542678..1d77c2b5789 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumArrays.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumArrays.java
@@ -310,17 +310,18 @@ public class EnumArrays {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to EnumArrays
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to EnumArrays
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!EnumArrays.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!EnumArrays.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in EnumArrays is not found in the empty JSON string", EnumArrays.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("just_symbol") != null && !jsonObj.get("just_symbol").isJsonNull()) && !jsonObj.get("just_symbol").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `just_symbol` to be a primitive type in the JSON string but got `%s`", jsonObj.get("just_symbol").toString()));
       }
@@ -367,8 +368,9 @@ public class EnumArrays {
 
            @Override
            public EnumArrays read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              EnumArrays instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumStringDiscriminator.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumStringDiscriminator.java
index 0158e6bc572..ebf31f32930 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumStringDiscriminator.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumStringDiscriminator.java
@@ -226,22 +226,22 @@ public class EnumStringDiscriminator {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to EnumStringDiscriminator
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to EnumStringDiscriminator
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!EnumStringDiscriminator.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!EnumStringDiscriminator.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in EnumStringDiscriminator is not found in the empty JSON string", EnumStringDiscriminator.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : EnumStringDiscriminator.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
   }
@@ -283,8 +283,9 @@ public class EnumStringDiscriminator {
 
            @Override
            public EnumStringDiscriminator read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              EnumStringDiscriminator instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumTest.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumTest.java
index 83f4a1c0984..7e3d4c7687a 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumTest.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EnumTest.java
@@ -658,24 +658,25 @@ public class EnumTest {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to EnumTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to EnumTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!EnumTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!EnumTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in EnumTest is not found in the empty JSON string", EnumTest.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : EnumTest.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("enum_string") != null && !jsonObj.get("enum_string").isJsonNull()) && !jsonObj.get("enum_string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `enum_string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("enum_string").toString()));
       }
@@ -721,8 +722,9 @@ public class EnumTest {
 
            @Override
            public EnumTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              EnumTest instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EquilateralTriangle.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EquilateralTriangle.java
index e82d60b1b03..8a9dc3147b7 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EquilateralTriangle.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/EquilateralTriangle.java
@@ -208,24 +208,25 @@ public class EquilateralTriangle {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to EquilateralTriangle
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to EquilateralTriangle
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!EquilateralTriangle.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!EquilateralTriangle.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in EquilateralTriangle is not found in the empty JSON string", EquilateralTriangle.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : EquilateralTriangle.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("shapeType").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `shapeType` to be a primitive type in the JSON string but got `%s`", jsonObj.get("shapeType").toString()));
       }
@@ -271,8 +272,9 @@ public class EquilateralTriangle {
 
            @Override
            public EquilateralTriangle read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              EquilateralTriangle instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
index 7165fd100e7..0911f149939 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FileSchemaTestClass.java
@@ -217,20 +217,21 @@ public class FileSchemaTestClass {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to FileSchemaTestClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to FileSchemaTestClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!FileSchemaTestClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!FileSchemaTestClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in FileSchemaTestClass is not found in the empty JSON string", FileSchemaTestClass.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `file`
       if (jsonObj.get("file") != null && !jsonObj.get("file").isJsonNull()) {
-        ModelFile.validateJsonObject(jsonObj.getAsJsonObject("file"));
+        ModelFile.validateJsonElement(jsonObj.get("file"));
       }
       if (jsonObj.get("files") != null && !jsonObj.get("files").isJsonNull()) {
         JsonArray jsonArrayfiles = jsonObj.getAsJsonArray("files");
@@ -242,7 +243,7 @@ public class FileSchemaTestClass {
 
           // validate the optional field `files` (array)
           for (int i = 0; i < jsonArrayfiles.size(); i++) {
-            ModelFile.validateJsonObject(jsonArrayfiles.get(i).getAsJsonObject());
+            ModelFile.validateJsonElement(jsonArrayfiles.get(i));
           };
         }
       }
@@ -285,8 +286,9 @@ public class FileSchemaTestClass {
 
            @Override
            public FileSchemaTestClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              FileSchemaTestClass instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Foo.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Foo.java
index 924f48c4607..ce0edf19397 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Foo.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Foo.java
@@ -178,17 +178,18 @@ public class Foo {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Foo
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Foo
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Foo.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Foo.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Foo is not found in the empty JSON string", Foo.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("bar") != null && !jsonObj.get("bar").isJsonNull()) && !jsonObj.get("bar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `bar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("bar").toString()));
       }
@@ -231,8 +232,9 @@ public class Foo {
 
            @Override
            public Foo read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Foo instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FooGetDefaultResponse.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FooGetDefaultResponse.java
index d2a41930f5b..4f903e13399 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FooGetDefaultResponse.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FooGetDefaultResponse.java
@@ -179,20 +179,21 @@ public class FooGetDefaultResponse {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to FooGetDefaultResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to FooGetDefaultResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!FooGetDefaultResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!FooGetDefaultResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in FooGetDefaultResponse is not found in the empty JSON string", FooGetDefaultResponse.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `string`
       if (jsonObj.get("string") != null && !jsonObj.get("string").isJsonNull()) {
-        Foo.validateJsonObject(jsonObj.getAsJsonObject("string"));
+        Foo.validateJsonElement(jsonObj.get("string"));
       }
   }
 
@@ -233,8 +234,9 @@ public class FooGetDefaultResponse {
 
            @Override
            public FooGetDefaultResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              FooGetDefaultResponse instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FormatTest.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FormatTest.java
index 68fcc38c476..e0d5a88be8a 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FormatTest.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FormatTest.java
@@ -645,24 +645,25 @@ public class FormatTest {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to FormatTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to FormatTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!FormatTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!FormatTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in FormatTest is not found in the empty JSON string", FormatTest.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : FormatTest.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("string") != null && !jsonObj.get("string").isJsonNull()) && !jsonObj.get("string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("string").toString()));
       }
@@ -720,8 +721,9 @@ public class FormatTest {
 
            @Override
            public FormatTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              FormatTest instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Fruit.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Fruit.java
index 1c1e1386b96..ed9086569f5 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Fruit.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Fruit.java
@@ -35,6 +35,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -54,6 +55,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -83,25 +85,23 @@ public class Fruit extends AbstractOpenApiSchema {
 
                     // check if the actual instance is of the type `Apple`
                     if (value.getActualInstance() instanceof Apple) {
-                        JsonObject obj = adapterApple.toJsonTree((Apple)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterApple.toJsonTree((Apple)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     // check if the actual instance is of the type `Banana`
                     if (value.getActualInstance() instanceof Banana) {
-                        JsonObject obj = adapterBanana.toJsonTree((Banana)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterBanana.toJsonTree((Banana)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: Apple, Banana");
                 }
 
                 @Override
                 public Fruit read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
 
                     int match = 0;
                     ArrayList<String> errorMessages = new ArrayList<>();
@@ -109,37 +109,36 @@ public class Fruit extends AbstractOpenApiSchema {
 
                     // deserialize Apple
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        Apple.validateJsonObject(jsonObject);
-                        actualAdapter = adapterApple;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Apple'");
+                      // validate the JSON object to see if any exception is thrown
+                      Apple.validateJsonElement(jsonElement);
+                      actualAdapter = adapterApple;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Apple'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Apple failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Apple'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Apple failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Apple'", e);
                     }
-
                     // deserialize Banana
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        Banana.validateJsonObject(jsonObject);
-                        actualAdapter = adapterBanana;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Banana'");
+                      // validate the JSON object to see if any exception is thrown
+                      Banana.validateJsonElement(jsonElement);
+                      actualAdapter = adapterBanana;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Banana'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Banana failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Banana'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Banana failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Banana'", e);
                     }
 
                     if (match == 1) {
                         Fruit ret = new Fruit();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for Fruit: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for Fruit: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -216,7 +215,6 @@ public class Fruit extends AbstractOpenApiSchema {
     public Apple getApple() throws ClassCastException {
         return (Apple)super.getActualInstance();
     }
-
     /**
      * Get the actual instance of `Banana`. If the actual instance is not `Banana`,
      * the ClassCastException will be thrown.
@@ -228,20 +226,19 @@ public class Fruit extends AbstractOpenApiSchema {
         return (Banana)super.getActualInstance();
     }
 
-
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Fruit
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Fruit
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
     // validate the json string with Apple
     try {
-      Apple.validateJsonObject(jsonObj);
+      Apple.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for Apple failed with `%s`.", e.getMessage()));
@@ -249,14 +246,14 @@ public class Fruit extends AbstractOpenApiSchema {
     }
     // validate the json string with Banana
     try {
-      Banana.validateJsonObject(jsonObj);
+      Banana.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for Banana failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for Fruit with oneOf schemas: Apple, Banana. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for Fruit with oneOf schemas: Apple, Banana. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FruitReq.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FruitReq.java
index 58397462bbb..cea09015a8c 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FruitReq.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/FruitReq.java
@@ -35,6 +35,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -54,6 +55,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -83,25 +85,23 @@ public class FruitReq extends AbstractOpenApiSchema {
 
                     // check if the actual instance is of the type `AppleReq`
                     if (value.getActualInstance() instanceof AppleReq) {
-                        JsonObject obj = adapterAppleReq.toJsonTree((AppleReq)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterAppleReq.toJsonTree((AppleReq)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     // check if the actual instance is of the type `BananaReq`
                     if (value.getActualInstance() instanceof BananaReq) {
-                        JsonObject obj = adapterBananaReq.toJsonTree((BananaReq)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterBananaReq.toJsonTree((BananaReq)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: AppleReq, BananaReq");
                 }
 
                 @Override
                 public FruitReq read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
 
                     int match = 0;
                     ArrayList<String> errorMessages = new ArrayList<>();
@@ -109,37 +109,36 @@ public class FruitReq extends AbstractOpenApiSchema {
 
                     // deserialize AppleReq
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        AppleReq.validateJsonObject(jsonObject);
-                        actualAdapter = adapterAppleReq;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'AppleReq'");
+                      // validate the JSON object to see if any exception is thrown
+                      AppleReq.validateJsonElement(jsonElement);
+                      actualAdapter = adapterAppleReq;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'AppleReq'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for AppleReq failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'AppleReq'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for AppleReq failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'AppleReq'", e);
                     }
-
                     // deserialize BananaReq
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        BananaReq.validateJsonObject(jsonObject);
-                        actualAdapter = adapterBananaReq;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'BananaReq'");
+                      // validate the JSON object to see if any exception is thrown
+                      BananaReq.validateJsonElement(jsonElement);
+                      actualAdapter = adapterBananaReq;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'BananaReq'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for BananaReq failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'BananaReq'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for BananaReq failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'BananaReq'", e);
                     }
 
                     if (match == 1) {
                         FruitReq ret = new FruitReq();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for FruitReq: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for FruitReq: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -221,7 +220,6 @@ public class FruitReq extends AbstractOpenApiSchema {
     public AppleReq getAppleReq() throws ClassCastException {
         return (AppleReq)super.getActualInstance();
     }
-
     /**
      * Get the actual instance of `BananaReq`. If the actual instance is not `BananaReq`,
      * the ClassCastException will be thrown.
@@ -233,20 +231,19 @@ public class FruitReq extends AbstractOpenApiSchema {
         return (BananaReq)super.getActualInstance();
     }
 
-
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to FruitReq
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to FruitReq
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
     // validate the json string with AppleReq
     try {
-      AppleReq.validateJsonObject(jsonObj);
+      AppleReq.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for AppleReq failed with `%s`.", e.getMessage()));
@@ -254,14 +251,14 @@ public class FruitReq extends AbstractOpenApiSchema {
     }
     // validate the json string with BananaReq
     try {
-      BananaReq.validateJsonObject(jsonObj);
+      BananaReq.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for BananaReq failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for FruitReq with oneOf schemas: AppleReq, BananaReq. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for FruitReq with oneOf schemas: AppleReq, BananaReq. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/GmFruit.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/GmFruit.java
index 5777b290e6b..2b76a56bc05 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/GmFruit.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/GmFruit.java
@@ -101,15 +101,15 @@ public class GmFruit extends AbstractOpenApiSchema {
                 @Override
                 public GmFruit read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
 
                     // deserialize Apple
                     try {
                         // validate the JSON object to see if any exception is thrown
-                        Apple.validateJsonObject(jsonObject);
+                        Apple.validateJsonElement(jsonElement);
                         log.log(Level.FINER, "Input data matches schema 'Apple'");
                         GmFruit ret = new GmFruit();
-                        ret.setActualInstance(adapterApple.fromJsonTree(jsonObject));
+                        ret.setActualInstance(adapterApple.fromJsonTree(jsonElement));
                         return ret;
                     } catch (Exception e) {
                         // deserialization failed, continue
@@ -119,10 +119,10 @@ public class GmFruit extends AbstractOpenApiSchema {
                     // deserialize Banana
                     try {
                         // validate the JSON object to see if any exception is thrown
-                        Banana.validateJsonObject(jsonObject);
+                        Banana.validateJsonElement(jsonElement);
                         log.log(Level.FINER, "Input data matches schema 'Banana'");
                         GmFruit ret = new GmFruit();
-                        ret.setActualInstance(adapterBanana.fromJsonTree(jsonObject));
+                        ret.setActualInstance(adapterBanana.fromJsonTree(jsonElement));
                         return ret;
                     } catch (Exception e) {
                         // deserialization failed, continue
@@ -130,7 +130,7 @@ public class GmFruit extends AbstractOpenApiSchema {
                     }
 
 
-                    throw new IOException(String.format("Failed deserialization for GmFruit: no class matched. JSON: %s", jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for GmFruit: no class matched. JSON: %s", jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -221,17 +221,17 @@ public class GmFruit extends AbstractOpenApiSchema {
 
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to GmFruit
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to GmFruit
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate anyOf schemas one by one
     int validCount = 0;
     // validate the json string with Apple
     try {
-      Apple.validateJsonObject(jsonObj);
+      Apple.validateJsonElement(jsonElement);
       return; // return earlier as at least one schema is valid with respect to the Json object
       //validCount++;
     } catch (Exception e) {
@@ -239,14 +239,14 @@ public class GmFruit extends AbstractOpenApiSchema {
     }
     // validate the json string with Banana
     try {
-      Banana.validateJsonObject(jsonObj);
+      Banana.validateJsonElement(jsonElement);
       return; // return earlier as at least one schema is valid with respect to the Json object
       //validCount++;
     } catch (Exception e) {
       // continue to the next one
     }
     if (validCount == 0) {
-      throw new IOException(String.format("The JSON string is invalid for GmFruit with anyOf schemas: Apple, Banana. JSON: %s", jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for GmFruit with anyOf schemas: Apple, Banana. JSON: %s", jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/GrandparentAnimal.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/GrandparentAnimal.java
index 3c648514d56..167c5e78d15 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/GrandparentAnimal.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/GrandparentAnimal.java
@@ -180,22 +180,22 @@ public class GrandparentAnimal {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to GrandparentAnimal
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to GrandparentAnimal
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!GrandparentAnimal.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!GrandparentAnimal.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in GrandparentAnimal is not found in the empty JSON string", GrandparentAnimal.openapiRequiredFields.toString()));
         }
       }
 
-      String discriminatorValue = jsonObj.get("pet_type").getAsString();
+      String discriminatorValue = jsonElement.getAsJsonObject().get("pet_type").getAsString();
       switch (discriminatorValue) {
         case "ParentPet":
-          ParentPet.validateJsonObject(jsonObj);
+          ParentPet.validateJsonElement(jsonElement);
           break;
         default:
           throw new IllegalArgumentException(String.format("The value of the `pet_type` field `%s` does not match any key defined in the discriminator's mapping.", discriminatorValue));
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
index 064fe7a922e..210f5026f7f 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/HasOnlyReadOnly.java
@@ -198,17 +198,18 @@ public class HasOnlyReadOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to HasOnlyReadOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to HasOnlyReadOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!HasOnlyReadOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!HasOnlyReadOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in HasOnlyReadOnly is not found in the empty JSON string", HasOnlyReadOnly.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("bar") != null && !jsonObj.get("bar").isJsonNull()) && !jsonObj.get("bar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `bar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("bar").toString()));
       }
@@ -254,8 +255,9 @@ public class HasOnlyReadOnly {
 
            @Override
            public HasOnlyReadOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              HasOnlyReadOnly instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/HealthCheckResult.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/HealthCheckResult.java
index 1f0b3c53047..6f6b304ae2e 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/HealthCheckResult.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/HealthCheckResult.java
@@ -190,17 +190,18 @@ public class HealthCheckResult {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to HealthCheckResult
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to HealthCheckResult
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!HealthCheckResult.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!HealthCheckResult.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in HealthCheckResult is not found in the empty JSON string", HealthCheckResult.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("NullableMessage") != null && !jsonObj.get("NullableMessage").isJsonNull()) && !jsonObj.get("NullableMessage").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `NullableMessage` to be a primitive type in the JSON string but got `%s`", jsonObj.get("NullableMessage").toString()));
       }
@@ -243,8 +244,9 @@ public class HealthCheckResult {
 
            @Override
            public HealthCheckResult read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              HealthCheckResult instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/IsoscelesTriangle.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/IsoscelesTriangle.java
index d60c61c2832..b5f13b8607c 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/IsoscelesTriangle.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/IsoscelesTriangle.java
@@ -162,32 +162,33 @@ public class IsoscelesTriangle {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to IsoscelesTriangle
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to IsoscelesTriangle
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!IsoscelesTriangle.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!IsoscelesTriangle.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in IsoscelesTriangle is not found in the empty JSON string", IsoscelesTriangle.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!IsoscelesTriangle.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `IsoscelesTriangle` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `IsoscelesTriangle` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : IsoscelesTriangle.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("shapeType").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `shapeType` to be a primitive type in the JSON string but got `%s`", jsonObj.get("shapeType").toString()));
       }
@@ -216,9 +217,9 @@ public class IsoscelesTriangle {
 
            @Override
            public IsoscelesTriangle read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Mammal.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Mammal.java
index 84b34dc1909..b0c27a52d95 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Mammal.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Mammal.java
@@ -35,6 +35,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -54,6 +55,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -70,9 +72,9 @@ public class Mammal extends AbstractOpenApiSchema {
                 return null; // this class only serializes 'Mammal' and its subtypes
             }
             final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
-            final TypeAdapter<Pig> adapterPig = gson.getDelegateAdapter(this, TypeToken.get(Pig.class));
             final TypeAdapter<Whale> adapterWhale = gson.getDelegateAdapter(this, TypeToken.get(Whale.class));
             final TypeAdapter<Zebra> adapterZebra = gson.getDelegateAdapter(this, TypeToken.get(Zebra.class));
+            final TypeAdapter<Pig> adapterPig = gson.getDelegateAdapter(this, TypeToken.get(Pig.class));
 
             return (TypeAdapter<T>) new TypeAdapter<Mammal>() {
                 @Override
@@ -82,34 +84,33 @@ public class Mammal extends AbstractOpenApiSchema {
                         return;
                     }
 
-                    // check if the actual instance is of the type `Pig`
-                    if (value.getActualInstance() instanceof Pig) {
-                        JsonObject obj = adapterPig.toJsonTree((Pig)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
-                    }
-
                     // check if the actual instance is of the type `Whale`
                     if (value.getActualInstance() instanceof Whale) {
-                        JsonObject obj = adapterWhale.toJsonTree((Whale)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterWhale.toJsonTree((Whale)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     // check if the actual instance is of the type `Zebra`
                     if (value.getActualInstance() instanceof Zebra) {
-                        JsonObject obj = adapterZebra.toJsonTree((Zebra)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterZebra.toJsonTree((Zebra)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
+                    }
+                    // check if the actual instance is of the type `Pig`
+                    if (value.getActualInstance() instanceof Pig) {
+                      JsonElement element = adapterPig.toJsonTree((Pig)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: Pig, Whale, Zebra");
                 }
 
                 @Override
                 public Mammal read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    JsonObject jsonObject = jsonElement.getAsJsonObject();
 
                     // use discriminator value for faster oneOf lookup
                     Mammal newMammal = new Mammal();
@@ -139,52 +140,50 @@ public class Mammal extends AbstractOpenApiSchema {
                     ArrayList<String> errorMessages = new ArrayList<>();
                     TypeAdapter actualAdapter = elementAdapter;
 
-                    // deserialize Pig
-                    try {
-                        // validate the JSON object to see if any exception is thrown
-                        Pig.validateJsonObject(jsonObject);
-                        actualAdapter = adapterPig;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Pig'");
-                    } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Pig failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Pig'", e);
-                    }
-
                     // deserialize Whale
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        Whale.validateJsonObject(jsonObject);
-                        actualAdapter = adapterWhale;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Whale'");
+                      // validate the JSON object to see if any exception is thrown
+                      Whale.validateJsonElement(jsonElement);
+                      actualAdapter = adapterWhale;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Whale'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Whale failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Whale'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Whale failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Whale'", e);
                     }
-
                     // deserialize Zebra
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        Zebra.validateJsonObject(jsonObject);
-                        actualAdapter = adapterZebra;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Zebra'");
+                      // validate the JSON object to see if any exception is thrown
+                      Zebra.validateJsonElement(jsonElement);
+                      actualAdapter = adapterZebra;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Zebra'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Zebra failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Zebra'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Zebra failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Zebra'", e);
+                    }
+                    // deserialize Pig
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      Pig.validateJsonElement(jsonElement);
+                      actualAdapter = adapterPig;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Pig'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Pig failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Pig'", e);
                     }
 
                     if (match == 1) {
                         Mammal ret = new Mammal();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for Mammal: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for Mammal: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -213,9 +212,9 @@ public class Mammal extends AbstractOpenApiSchema {
     }
 
     static {
-        schemas.put("Pig", Pig.class);
         schemas.put("Whale", Whale.class);
         schemas.put("Zebra", Zebra.class);
+        schemas.put("Pig", Pig.class);
     }
 
     @Override
@@ -233,11 +232,6 @@ public class Mammal extends AbstractOpenApiSchema {
      */
     @Override
     public void setActualInstance(Object instance) {
-        if (instance instanceof Pig) {
-            super.setActualInstance(instance);
-            return;
-        }
-
         if (instance instanceof Whale) {
             super.setActualInstance(instance);
             return;
@@ -248,6 +242,11 @@ public class Mammal extends AbstractOpenApiSchema {
             return;
         }
 
+        if (instance instanceof Pig) {
+            super.setActualInstance(instance);
+            return;
+        }
+
         throw new RuntimeException("Invalid instance type. Must be Pig, Whale, Zebra");
     }
 
@@ -262,17 +261,6 @@ public class Mammal extends AbstractOpenApiSchema {
         return super.getActualInstance();
     }
 
-    /**
-     * Get the actual instance of `Pig`. If the actual instance is not `Pig`,
-     * the ClassCastException will be thrown.
-     *
-     * @return The actual instance of `Pig`
-     * @throws ClassCastException if the instance is not `Pig`
-     */
-    public Pig getPig() throws ClassCastException {
-        return (Pig)super.getActualInstance();
-    }
-
     /**
      * Get the actual instance of `Whale`. If the actual instance is not `Whale`,
      * the ClassCastException will be thrown.
@@ -283,7 +271,6 @@ public class Mammal extends AbstractOpenApiSchema {
     public Whale getWhale() throws ClassCastException {
         return (Whale)super.getActualInstance();
     }
-
     /**
      * Get the actual instance of `Zebra`. If the actual instance is not `Zebra`,
      * the ClassCastException will be thrown.
@@ -294,29 +281,30 @@ public class Mammal extends AbstractOpenApiSchema {
     public Zebra getZebra() throws ClassCastException {
         return (Zebra)super.getActualInstance();
     }
-
+    /**
+     * Get the actual instance of `Pig`. If the actual instance is not `Pig`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `Pig`
+     * @throws ClassCastException if the instance is not `Pig`
+     */
+    public Pig getPig() throws ClassCastException {
+        return (Pig)super.getActualInstance();
+    }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Mammal
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Mammal
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
-    // validate the json string with Pig
-    try {
-      Pig.validateJsonObject(jsonObj);
-      validCount++;
-    } catch (Exception e) {
-      errorMessages.add(String.format("Deserialization for Pig failed with `%s`.", e.getMessage()));
-      // continue to the next one
-    }
     // validate the json string with Whale
     try {
-      Whale.validateJsonObject(jsonObj);
+      Whale.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for Whale failed with `%s`.", e.getMessage()));
@@ -324,14 +312,22 @@ public class Mammal extends AbstractOpenApiSchema {
     }
     // validate the json string with Zebra
     try {
-      Zebra.validateJsonObject(jsonObj);
+      Zebra.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for Zebra failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
+    // validate the json string with Pig
+    try {
+      Pig.validateJsonElement(jsonElement);
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for Pig failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for Mammal with oneOf schemas: Pig, Whale, Zebra. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for Mammal with oneOf schemas: Pig, Whale, Zebra. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/MapTest.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/MapTest.java
index 7599036f629..70f56395e0d 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/MapTest.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/MapTest.java
@@ -343,17 +343,18 @@ public class MapTest {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to MapTest
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to MapTest
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!MapTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!MapTest.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in MapTest is not found in the empty JSON string", MapTest.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -393,8 +394,9 @@ public class MapTest {
 
            @Override
            public MapTest read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              MapTest instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
index e79c229a59d..0a2af49b916 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/MixedPropertiesAndAdditionalPropertiesClass.java
@@ -247,17 +247,18 @@ public class MixedPropertiesAndAdditionalPropertiesClass {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to MixedPropertiesAndAdditionalPropertiesClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to MixedPropertiesAndAdditionalPropertiesClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in MixedPropertiesAndAdditionalPropertiesClass is not found in the empty JSON string", MixedPropertiesAndAdditionalPropertiesClass.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("uuid") != null && !jsonObj.get("uuid").isJsonNull()) && !jsonObj.get("uuid").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `uuid` to be a primitive type in the JSON string but got `%s`", jsonObj.get("uuid").toString()));
       }
@@ -300,8 +301,9 @@ public class MixedPropertiesAndAdditionalPropertiesClass {
 
            @Override
            public MixedPropertiesAndAdditionalPropertiesClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              MixedPropertiesAndAdditionalPropertiesClass instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Model200Response.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Model200Response.java
index bfea09332bc..12138c18d5c 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Model200Response.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Model200Response.java
@@ -206,17 +206,18 @@ public class Model200Response {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Model200Response
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Model200Response
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Model200Response.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Model200Response.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Model200Response is not found in the empty JSON string", Model200Response.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("class") != null && !jsonObj.get("class").isJsonNull()) && !jsonObj.get("class").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `class` to be a primitive type in the JSON string but got `%s`", jsonObj.get("class").toString()));
       }
@@ -259,8 +260,9 @@ public class Model200Response {
 
            @Override
            public Model200Response read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Model200Response instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelApiResponse.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelApiResponse.java
index 3dc9cf29576..ba7858ea376 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelApiResponse.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelApiResponse.java
@@ -234,17 +234,18 @@ public class ModelApiResponse {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelApiResponse
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelApiResponse
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelApiResponse.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelApiResponse is not found in the empty JSON string", ModelApiResponse.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -290,8 +291,9 @@ public class ModelApiResponse {
 
            @Override
            public ModelApiResponse read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelApiResponse instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelFile.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelFile.java
index a1cbb649bd2..dd7afcfd23c 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelFile.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelFile.java
@@ -178,17 +178,18 @@ public class ModelFile {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelFile
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelFile
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelFile.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelFile.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelFile is not found in the empty JSON string", ModelFile.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("sourceURI") != null && !jsonObj.get("sourceURI").isJsonNull()) && !jsonObj.get("sourceURI").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `sourceURI` to be a primitive type in the JSON string but got `%s`", jsonObj.get("sourceURI").toString()));
       }
@@ -231,8 +232,9 @@ public class ModelFile {
 
            @Override
            public ModelFile read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelFile instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelList.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelList.java
index f9e57945da6..d3f9593baab 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelList.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelList.java
@@ -178,17 +178,18 @@ public class ModelList {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelList
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelList
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelList.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelList.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelList is not found in the empty JSON string", ModelList.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("123-list") != null && !jsonObj.get("123-list").isJsonNull()) && !jsonObj.get("123-list").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `123-list` to be a primitive type in the JSON string but got `%s`", jsonObj.get("123-list").toString()));
       }
@@ -231,8 +232,9 @@ public class ModelList {
 
            @Override
            public ModelList read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelList instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelReturn.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelReturn.java
index 1d5a946e4f8..4e63e4b9d5f 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelReturn.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ModelReturn.java
@@ -178,17 +178,18 @@ public class ModelReturn {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ModelReturn
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ModelReturn
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ModelReturn.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ModelReturn.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ModelReturn is not found in the empty JSON string", ModelReturn.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -228,8 +229,9 @@ public class ModelReturn {
 
            @Override
            public ModelReturn read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ModelReturn instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Name.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Name.java
index a9b3831f577..e7f990e1429 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Name.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Name.java
@@ -255,24 +255,25 @@ public class Name {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Name
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Name
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Name.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Name.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Name is not found in the empty JSON string", Name.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Name.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("property") != null && !jsonObj.get("property").isJsonNull()) && !jsonObj.get("property").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `property` to be a primitive type in the JSON string but got `%s`", jsonObj.get("property").toString()));
       }
@@ -315,8 +316,9 @@ public class Name {
 
            @Override
            public Name read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Name instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableClass.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableClass.java
index 71d85dc349c..a6b7762819d 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableClass.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableClass.java
@@ -507,25 +507,26 @@ public class NullableClass {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to NullableClass
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to NullableClass
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!NullableClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!NullableClass.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in NullableClass is not found in the empty JSON string", NullableClass.openapiRequiredFields.toString()));
         }
       }
 
-      Set<Entry<String, JsonElement>> entries = jsonObj.entrySet();
+      Set<Entry<String, JsonElement>> entries = jsonElement.getAsJsonObject().entrySet();
       // check to see if the JSON string contains additional fields
       for (Entry<String, JsonElement> entry : entries) {
         if (!NullableClass.openapiFields.contains(entry.getKey())) {
-          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `NullableClass` properties. JSON: %s", entry.getKey(), jsonObj.toString()));
+          throw new IllegalArgumentException(String.format("The field `%s` in the JSON string is not defined in the `NullableClass` properties. JSON: %s", entry.getKey(), jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("string_prop") != null && !jsonObj.get("string_prop").isJsonNull()) && !jsonObj.get("string_prop").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `string_prop` to be a primitive type in the JSON string but got `%s`", jsonObj.get("string_prop").toString()));
       }
@@ -563,9 +564,9 @@ public class NullableClass {
 
            @Override
            public NullableClass read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
-             return thisAdapter.fromJsonTree(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             return thisAdapter.fromJsonTree(jsonElement);
            }
 
        }.nullSafe();
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableShape.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableShape.java
index 4ce082ae5f6..be908198855 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableShape.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableShape.java
@@ -34,6 +34,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -53,6 +54,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -69,8 +71,8 @@ public class NullableShape extends AbstractOpenApiSchema {
                 return null; // this class only serializes 'NullableShape' and its subtypes
             }
             final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
-            final TypeAdapter<Quadrilateral> adapterQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(Quadrilateral.class));
             final TypeAdapter<Triangle> adapterTriangle = gson.getDelegateAdapter(this, TypeToken.get(Triangle.class));
+            final TypeAdapter<Quadrilateral> adapterQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(Quadrilateral.class));
 
             return (TypeAdapter<T>) new TypeAdapter<NullableShape>() {
                 @Override
@@ -80,27 +82,27 @@ public class NullableShape extends AbstractOpenApiSchema {
                         return;
                     }
 
-                    // check if the actual instance is of the type `Quadrilateral`
-                    if (value.getActualInstance() instanceof Quadrilateral) {
-                        JsonObject obj = adapterQuadrilateral.toJsonTree((Quadrilateral)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
-                    }
-
                     // check if the actual instance is of the type `Triangle`
                     if (value.getActualInstance() instanceof Triangle) {
-                        JsonObject obj = adapterTriangle.toJsonTree((Triangle)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterTriangle.toJsonTree((Triangle)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
+                    }
+                    // check if the actual instance is of the type `Quadrilateral`
+                    if (value.getActualInstance() instanceof Quadrilateral) {
+                      JsonElement element = adapterQuadrilateral.toJsonTree((Quadrilateral)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: Quadrilateral, Triangle");
                 }
 
                 @Override
                 public NullableShape read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    JsonObject jsonObject = jsonElement.getAsJsonObject();
 
                     // use discriminator value for faster oneOf lookup
                     NullableShape newNullableShape = new NullableShape();
@@ -126,39 +128,38 @@ public class NullableShape extends AbstractOpenApiSchema {
                     ArrayList<String> errorMessages = new ArrayList<>();
                     TypeAdapter actualAdapter = elementAdapter;
 
-                    // deserialize Quadrilateral
-                    try {
-                        // validate the JSON object to see if any exception is thrown
-                        Quadrilateral.validateJsonObject(jsonObject);
-                        actualAdapter = adapterQuadrilateral;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Quadrilateral'");
-                    } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Quadrilateral'", e);
-                    }
-
                     // deserialize Triangle
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        Triangle.validateJsonObject(jsonObject);
-                        actualAdapter = adapterTriangle;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Triangle'");
+                      // validate the JSON object to see if any exception is thrown
+                      Triangle.validateJsonElement(jsonElement);
+                      actualAdapter = adapterTriangle;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Triangle'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Triangle'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Triangle'", e);
+                    }
+                    // deserialize Quadrilateral
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      Quadrilateral.validateJsonElement(jsonElement);
+                      actualAdapter = adapterQuadrilateral;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Quadrilateral'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Quadrilateral'", e);
                     }
 
                     if (match == 1) {
                         NullableShape ret = new NullableShape();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for NullableShape: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for NullableShape: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -182,8 +183,8 @@ public class NullableShape extends AbstractOpenApiSchema {
     }
 
     static {
-        schemas.put("Quadrilateral", Quadrilateral.class);
         schemas.put("Triangle", Triangle.class);
+        schemas.put("Quadrilateral", Quadrilateral.class);
     }
 
     @Override
@@ -206,12 +207,12 @@ public class NullableShape extends AbstractOpenApiSchema {
            return;
         }
 
-        if (instance instanceof Quadrilateral) {
+        if (instance instanceof Triangle) {
             super.setActualInstance(instance);
             return;
         }
 
-        if (instance instanceof Triangle) {
+        if (instance instanceof Quadrilateral) {
             super.setActualInstance(instance);
             return;
         }
@@ -230,6 +231,16 @@ public class NullableShape extends AbstractOpenApiSchema {
         return super.getActualInstance();
     }
 
+    /**
+     * Get the actual instance of `Triangle`. If the actual instance is not `Triangle`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `Triangle`
+     * @throws ClassCastException if the instance is not `Triangle`
+     */
+    public Triangle getTriangle() throws ClassCastException {
+        return (Triangle)super.getActualInstance();
+    }
     /**
      * Get the actual instance of `Quadrilateral`. If the actual instance is not `Quadrilateral`,
      * the ClassCastException will be thrown.
@@ -241,46 +252,34 @@ public class NullableShape extends AbstractOpenApiSchema {
         return (Quadrilateral)super.getActualInstance();
     }
 
-    /**
-     * Get the actual instance of `Triangle`. If the actual instance is not `Triangle`,
-     * the ClassCastException will be thrown.
-     *
-     * @return The actual instance of `Triangle`
-     * @throws ClassCastException if the instance is not `Triangle`
-     */
-    public Triangle getTriangle() throws ClassCastException {
-        return (Triangle)super.getActualInstance();
-    }
-
-
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to NullableShape
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to NullableShape
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
-    // validate the json string with Quadrilateral
-    try {
-      Quadrilateral.validateJsonObject(jsonObj);
-      validCount++;
-    } catch (Exception e) {
-      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
-      // continue to the next one
-    }
     // validate the json string with Triangle
     try {
-      Triangle.validateJsonObject(jsonObj);
+      Triangle.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
+    // validate the json string with Quadrilateral
+    try {
+      Quadrilateral.validateJsonElement(jsonElement);
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for NullableShape with oneOf schemas: Quadrilateral, Triangle. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for NullableShape with oneOf schemas: Quadrilateral, Triangle. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NumberOnly.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NumberOnly.java
index 857c0e5f763..1788fcf64fb 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NumberOnly.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NumberOnly.java
@@ -179,17 +179,18 @@ public class NumberOnly {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to NumberOnly
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to NumberOnly
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!NumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!NumberOnly.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in NumberOnly is not found in the empty JSON string", NumberOnly.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
   }
 
   public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
@@ -229,8 +230,9 @@ public class NumberOnly {
 
            @Override
            public NumberOnly read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              NumberOnly instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ObjectWithDeprecatedFields.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ObjectWithDeprecatedFields.java
index 69f33902609..0ae68a87be3 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ObjectWithDeprecatedFields.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ObjectWithDeprecatedFields.java
@@ -289,23 +289,24 @@ public class ObjectWithDeprecatedFields {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ObjectWithDeprecatedFields
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ObjectWithDeprecatedFields
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ObjectWithDeprecatedFields.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ObjectWithDeprecatedFields.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ObjectWithDeprecatedFields is not found in the empty JSON string", ObjectWithDeprecatedFields.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("uuid") != null && !jsonObj.get("uuid").isJsonNull()) && !jsonObj.get("uuid").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `uuid` to be a primitive type in the JSON string but got `%s`", jsonObj.get("uuid").toString()));
       }
       // validate the optional field `deprecatedRef`
       if (jsonObj.get("deprecatedRef") != null && !jsonObj.get("deprecatedRef").isJsonNull()) {
-        DeprecatedObject.validateJsonObject(jsonObj.getAsJsonObject("deprecatedRef"));
+        DeprecatedObject.validateJsonElement(jsonObj.get("deprecatedRef"));
       }
       // ensure the optional json data is an array if present
       if (jsonObj.get("bars") != null && !jsonObj.get("bars").isJsonArray()) {
@@ -350,8 +351,9 @@ public class ObjectWithDeprecatedFields {
 
            @Override
            public ObjectWithDeprecatedFields read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ObjectWithDeprecatedFields instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Order.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Order.java
index bc091d2721d..d0492bf3538 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Order.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Order.java
@@ -368,17 +368,18 @@ public class Order {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Order
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Order
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Order.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Order is not found in the empty JSON string", Order.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
       }
@@ -421,8 +422,9 @@ public class Order {
 
            @Override
            public Order read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Order instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/OuterComposite.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/OuterComposite.java
index aabde2fe5de..194507fa828 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/OuterComposite.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/OuterComposite.java
@@ -235,17 +235,18 @@ public class OuterComposite {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to OuterComposite
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to OuterComposite
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!OuterComposite.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!OuterComposite.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in OuterComposite is not found in the empty JSON string", OuterComposite.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("my_string") != null && !jsonObj.get("my_string").isJsonNull()) && !jsonObj.get("my_string").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `my_string` to be a primitive type in the JSON string but got `%s`", jsonObj.get("my_string").toString()));
       }
@@ -288,8 +289,9 @@ public class OuterComposite {
 
            @Override
            public OuterComposite read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              OuterComposite instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ParentPet.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ParentPet.java
index 44cdd8943ef..c98181f2fc9 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ParentPet.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ParentPet.java
@@ -154,22 +154,22 @@ public class ParentPet extends GrandparentAnimal {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ParentPet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ParentPet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ParentPet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ParentPet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ParentPet is not found in the empty JSON string", ParentPet.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : ParentPet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
   }
@@ -211,8 +211,9 @@ public class ParentPet extends GrandparentAnimal {
 
            @Override
            public ParentPet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ParentPet instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pet.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pet.java
index 48cb5e9a7a8..6a6484541db 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pet.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pet.java
@@ -389,27 +389,28 @@ public class Pet {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pet
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pet
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Pet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Pet is not found in the empty JSON string", Pet.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Pet.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -430,7 +431,7 @@ public class Pet {
 
           // validate the optional field `tags` (array)
           for (int i = 0; i < jsonArraytags.size(); i++) {
-            Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+            Tag.validateJsonElement(jsonArraytags.get(i));
           };
         }
       }
@@ -476,8 +477,9 @@ public class Pet {
 
            @Override
            public Pet read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Pet instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/PetWithRequiredTags.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/PetWithRequiredTags.java
index 57743c9691d..5bf289f476f 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/PetWithRequiredTags.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/PetWithRequiredTags.java
@@ -390,27 +390,28 @@ public class PetWithRequiredTags {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to PetWithRequiredTags
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to PetWithRequiredTags
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!PetWithRequiredTags.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!PetWithRequiredTags.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in PetWithRequiredTags is not found in the empty JSON string", PetWithRequiredTags.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : PetWithRequiredTags.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       // validate the optional field `category`
       if (jsonObj.get("category") != null && !jsonObj.get("category").isJsonNull()) {
-        Category.validateJsonObject(jsonObj.getAsJsonObject("category"));
+        Category.validateJsonElement(jsonObj.get("category"));
       }
       if (!jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
@@ -429,7 +430,7 @@ public class PetWithRequiredTags {
       JsonArray jsonArraytags = jsonObj.getAsJsonArray("tags");
       // validate the required field `tags` (array)
       for (int i = 0; i < jsonArraytags.size(); i++) {
-        Tag.validateJsonObject(jsonArraytags.get(i).getAsJsonObject());
+        Tag.validateJsonElement(jsonArraytags.get(i));
       };
       if ((jsonObj.get("status") != null && !jsonObj.get("status").isJsonNull()) && !jsonObj.get("status").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `status` to be a primitive type in the JSON string but got `%s`", jsonObj.get("status").toString()));
@@ -473,8 +474,9 @@ public class PetWithRequiredTags {
 
            @Override
            public PetWithRequiredTags read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              PetWithRequiredTags instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pig.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pig.java
index d12d4f2120d..ba2fb7461cb 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pig.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pig.java
@@ -34,6 +34,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -53,6 +54,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -82,25 +84,25 @@ public class Pig extends AbstractOpenApiSchema {
 
                     // check if the actual instance is of the type `BasquePig`
                     if (value.getActualInstance() instanceof BasquePig) {
-                        JsonObject obj = adapterBasquePig.toJsonTree((BasquePig)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterBasquePig.toJsonTree((BasquePig)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     // check if the actual instance is of the type `DanishPig`
                     if (value.getActualInstance() instanceof DanishPig) {
-                        JsonObject obj = adapterDanishPig.toJsonTree((DanishPig)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterDanishPig.toJsonTree((DanishPig)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: BasquePig, DanishPig");
                 }
 
                 @Override
                 public Pig read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    JsonObject jsonObject = jsonElement.getAsJsonObject();
 
                     // use discriminator value for faster oneOf lookup
                     Pig newPig = new Pig();
@@ -128,37 +130,36 @@ public class Pig extends AbstractOpenApiSchema {
 
                     // deserialize BasquePig
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        BasquePig.validateJsonObject(jsonObject);
-                        actualAdapter = adapterBasquePig;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'BasquePig'");
+                      // validate the JSON object to see if any exception is thrown
+                      BasquePig.validateJsonElement(jsonElement);
+                      actualAdapter = adapterBasquePig;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'BasquePig'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for BasquePig failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'BasquePig'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for BasquePig failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'BasquePig'", e);
                     }
-
                     // deserialize DanishPig
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        DanishPig.validateJsonObject(jsonObject);
-                        actualAdapter = adapterDanishPig;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'DanishPig'");
+                      // validate the JSON object to see if any exception is thrown
+                      DanishPig.validateJsonElement(jsonElement);
+                      actualAdapter = adapterDanishPig;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'DanishPig'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for DanishPig failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'DanishPig'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for DanishPig failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'DanishPig'", e);
                     }
 
                     if (match == 1) {
                         Pig ret = new Pig();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for Pig: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for Pig: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -235,7 +236,6 @@ public class Pig extends AbstractOpenApiSchema {
     public BasquePig getBasquePig() throws ClassCastException {
         return (BasquePig)super.getActualInstance();
     }
-
     /**
      * Get the actual instance of `DanishPig`. If the actual instance is not `DanishPig`,
      * the ClassCastException will be thrown.
@@ -247,20 +247,19 @@ public class Pig extends AbstractOpenApiSchema {
         return (DanishPig)super.getActualInstance();
     }
 
-
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Pig
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Pig
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
     // validate the json string with BasquePig
     try {
-      BasquePig.validateJsonObject(jsonObj);
+      BasquePig.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for BasquePig failed with `%s`.", e.getMessage()));
@@ -268,14 +267,14 @@ public class Pig extends AbstractOpenApiSchema {
     }
     // validate the json string with DanishPig
     try {
-      DanishPig.validateJsonObject(jsonObj);
+      DanishPig.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for DanishPig failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for Pig with oneOf schemas: BasquePig, DanishPig. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for Pig with oneOf schemas: BasquePig, DanishPig. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Quadrilateral.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Quadrilateral.java
index c43ad2d1cf7..78b2897e0ac 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Quadrilateral.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Quadrilateral.java
@@ -34,6 +34,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -53,6 +54,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -69,8 +71,8 @@ public class Quadrilateral extends AbstractOpenApiSchema {
                 return null; // this class only serializes 'Quadrilateral' and its subtypes
             }
             final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
-            final TypeAdapter<ComplexQuadrilateral> adapterComplexQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(ComplexQuadrilateral.class));
             final TypeAdapter<SimpleQuadrilateral> adapterSimpleQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(SimpleQuadrilateral.class));
+            final TypeAdapter<ComplexQuadrilateral> adapterComplexQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(ComplexQuadrilateral.class));
 
             return (TypeAdapter<T>) new TypeAdapter<Quadrilateral>() {
                 @Override
@@ -80,27 +82,27 @@ public class Quadrilateral extends AbstractOpenApiSchema {
                         return;
                     }
 
-                    // check if the actual instance is of the type `ComplexQuadrilateral`
-                    if (value.getActualInstance() instanceof ComplexQuadrilateral) {
-                        JsonObject obj = adapterComplexQuadrilateral.toJsonTree((ComplexQuadrilateral)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
-                    }
-
                     // check if the actual instance is of the type `SimpleQuadrilateral`
                     if (value.getActualInstance() instanceof SimpleQuadrilateral) {
-                        JsonObject obj = adapterSimpleQuadrilateral.toJsonTree((SimpleQuadrilateral)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterSimpleQuadrilateral.toJsonTree((SimpleQuadrilateral)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
+                    }
+                    // check if the actual instance is of the type `ComplexQuadrilateral`
+                    if (value.getActualInstance() instanceof ComplexQuadrilateral) {
+                      JsonElement element = adapterComplexQuadrilateral.toJsonTree((ComplexQuadrilateral)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: ComplexQuadrilateral, SimpleQuadrilateral");
                 }
 
                 @Override
                 public Quadrilateral read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    JsonObject jsonObject = jsonElement.getAsJsonObject();
 
                     // use discriminator value for faster oneOf lookup
                     Quadrilateral newQuadrilateral = new Quadrilateral();
@@ -126,39 +128,38 @@ public class Quadrilateral extends AbstractOpenApiSchema {
                     ArrayList<String> errorMessages = new ArrayList<>();
                     TypeAdapter actualAdapter = elementAdapter;
 
-                    // deserialize ComplexQuadrilateral
-                    try {
-                        // validate the JSON object to see if any exception is thrown
-                        ComplexQuadrilateral.validateJsonObject(jsonObject);
-                        actualAdapter = adapterComplexQuadrilateral;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'ComplexQuadrilateral'");
-                    } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for ComplexQuadrilateral failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'ComplexQuadrilateral'", e);
-                    }
-
                     // deserialize SimpleQuadrilateral
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        SimpleQuadrilateral.validateJsonObject(jsonObject);
-                        actualAdapter = adapterSimpleQuadrilateral;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'SimpleQuadrilateral'");
+                      // validate the JSON object to see if any exception is thrown
+                      SimpleQuadrilateral.validateJsonElement(jsonElement);
+                      actualAdapter = adapterSimpleQuadrilateral;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'SimpleQuadrilateral'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for SimpleQuadrilateral failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'SimpleQuadrilateral'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for SimpleQuadrilateral failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'SimpleQuadrilateral'", e);
+                    }
+                    // deserialize ComplexQuadrilateral
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      ComplexQuadrilateral.validateJsonElement(jsonElement);
+                      actualAdapter = adapterComplexQuadrilateral;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'ComplexQuadrilateral'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for ComplexQuadrilateral failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'ComplexQuadrilateral'", e);
                     }
 
                     if (match == 1) {
                         Quadrilateral ret = new Quadrilateral();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for Quadrilateral: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for Quadrilateral: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -182,8 +183,8 @@ public class Quadrilateral extends AbstractOpenApiSchema {
     }
 
     static {
-        schemas.put("ComplexQuadrilateral", ComplexQuadrilateral.class);
         schemas.put("SimpleQuadrilateral", SimpleQuadrilateral.class);
+        schemas.put("ComplexQuadrilateral", ComplexQuadrilateral.class);
     }
 
     @Override
@@ -201,12 +202,12 @@ public class Quadrilateral extends AbstractOpenApiSchema {
      */
     @Override
     public void setActualInstance(Object instance) {
-        if (instance instanceof ComplexQuadrilateral) {
+        if (instance instanceof SimpleQuadrilateral) {
             super.setActualInstance(instance);
             return;
         }
 
-        if (instance instanceof SimpleQuadrilateral) {
+        if (instance instanceof ComplexQuadrilateral) {
             super.setActualInstance(instance);
             return;
         }
@@ -225,6 +226,16 @@ public class Quadrilateral extends AbstractOpenApiSchema {
         return super.getActualInstance();
     }
 
+    /**
+     * Get the actual instance of `SimpleQuadrilateral`. If the actual instance is not `SimpleQuadrilateral`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `SimpleQuadrilateral`
+     * @throws ClassCastException if the instance is not `SimpleQuadrilateral`
+     */
+    public SimpleQuadrilateral getSimpleQuadrilateral() throws ClassCastException {
+        return (SimpleQuadrilateral)super.getActualInstance();
+    }
     /**
      * Get the actual instance of `ComplexQuadrilateral`. If the actual instance is not `ComplexQuadrilateral`,
      * the ClassCastException will be thrown.
@@ -236,46 +247,34 @@ public class Quadrilateral extends AbstractOpenApiSchema {
         return (ComplexQuadrilateral)super.getActualInstance();
     }
 
-    /**
-     * Get the actual instance of `SimpleQuadrilateral`. If the actual instance is not `SimpleQuadrilateral`,
-     * the ClassCastException will be thrown.
-     *
-     * @return The actual instance of `SimpleQuadrilateral`
-     * @throws ClassCastException if the instance is not `SimpleQuadrilateral`
-     */
-    public SimpleQuadrilateral getSimpleQuadrilateral() throws ClassCastException {
-        return (SimpleQuadrilateral)super.getActualInstance();
-    }
-
-
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Quadrilateral
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Quadrilateral
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
-    // validate the json string with ComplexQuadrilateral
-    try {
-      ComplexQuadrilateral.validateJsonObject(jsonObj);
-      validCount++;
-    } catch (Exception e) {
-      errorMessages.add(String.format("Deserialization for ComplexQuadrilateral failed with `%s`.", e.getMessage()));
-      // continue to the next one
-    }
     // validate the json string with SimpleQuadrilateral
     try {
-      SimpleQuadrilateral.validateJsonObject(jsonObj);
+      SimpleQuadrilateral.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for SimpleQuadrilateral failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
+    // validate the json string with ComplexQuadrilateral
+    try {
+      ComplexQuadrilateral.validateJsonElement(jsonElement);
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for ComplexQuadrilateral failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for Quadrilateral with oneOf schemas: ComplexQuadrilateral, SimpleQuadrilateral. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for Quadrilateral with oneOf schemas: ComplexQuadrilateral, SimpleQuadrilateral. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/QuadrilateralInterface.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/QuadrilateralInterface.java
index 089d1b8210c..9e63ace354f 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/QuadrilateralInterface.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/QuadrilateralInterface.java
@@ -179,24 +179,25 @@ public class QuadrilateralInterface {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to QuadrilateralInterface
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to QuadrilateralInterface
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!QuadrilateralInterface.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!QuadrilateralInterface.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in QuadrilateralInterface is not found in the empty JSON string", QuadrilateralInterface.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : QuadrilateralInterface.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("quadrilateralType").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `quadrilateralType` to be a primitive type in the JSON string but got `%s`", jsonObj.get("quadrilateralType").toString()));
       }
@@ -239,8 +240,9 @@ public class QuadrilateralInterface {
 
            @Override
            public QuadrilateralInterface read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              QuadrilateralInterface instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
index 1c54ee697c9..4de9a26eda7 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ReadOnlyFirst.java
@@ -205,17 +205,18 @@ public class ReadOnlyFirst {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ReadOnlyFirst
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ReadOnlyFirst
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ReadOnlyFirst.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ReadOnlyFirst.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ReadOnlyFirst is not found in the empty JSON string", ReadOnlyFirst.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("bar") != null && !jsonObj.get("bar").isJsonNull()) && !jsonObj.get("bar").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `bar` to be a primitive type in the JSON string but got `%s`", jsonObj.get("bar").toString()));
       }
@@ -261,8 +262,9 @@ public class ReadOnlyFirst {
 
            @Override
            public ReadOnlyFirst read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ReadOnlyFirst instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Scalar.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Scalar.java
new file mode 100644
index 00000000000..403abb636cc
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Scalar.java
@@ -0,0 +1,332 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import java.util.Objects;
+import java.util.Arrays;
+import java.math.BigDecimal;
+
+
+
+import java.io.IOException;
+import java.lang.reflect.Type;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParseException;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.JsonPrimitive;
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.annotations.SerializedName;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonParseException;
+
+import org.openapitools.client.JSON;
+
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
+public class Scalar extends AbstractOpenApiSchema {
+    private static final Logger log = Logger.getLogger(Scalar.class.getName());
+
+    public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+        @SuppressWarnings("unchecked")
+        @Override
+        public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+            if (!Scalar.class.isAssignableFrom(type.getRawType())) {
+                return null; // this class only serializes 'Scalar' and its subtypes
+            }
+            final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+            final TypeAdapter<String> adapterString = gson.getDelegateAdapter(this, TypeToken.get(String.class));
+            final TypeAdapter<BigDecimal> adapterBigDecimal = gson.getDelegateAdapter(this, TypeToken.get(BigDecimal.class));
+            final TypeAdapter<Boolean> adapterBoolean = gson.getDelegateAdapter(this, TypeToken.get(Boolean.class));
+
+            return (TypeAdapter<T>) new TypeAdapter<Scalar>() {
+                @Override
+                public void write(JsonWriter out, Scalar value) throws IOException {
+                    if (value == null || value.getActualInstance() == null) {
+                        elementAdapter.write(out, null);
+                        return;
+                    }
+
+                    // check if the actual instance is of the type `String`
+                    if (value.getActualInstance() instanceof String) {
+                      JsonPrimitive primitive = adapterString.toJsonTree((String)value.getActualInstance()).getAsJsonPrimitive();
+                      elementAdapter.write(out, primitive);
+                      return;
+                    }
+                    // check if the actual instance is of the type `BigDecimal`
+                    if (value.getActualInstance() instanceof BigDecimal) {
+                      JsonPrimitive primitive = adapterBigDecimal.toJsonTree((BigDecimal)value.getActualInstance()).getAsJsonPrimitive();
+                      elementAdapter.write(out, primitive);
+                      return;
+                    }
+                    // check if the actual instance is of the type `Boolean`
+                    if (value.getActualInstance() instanceof Boolean) {
+                      JsonPrimitive primitive = adapterBoolean.toJsonTree((Boolean)value.getActualInstance()).getAsJsonPrimitive();
+                      elementAdapter.write(out, primitive);
+                      return;
+                    }
+                    throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: BigDecimal, Boolean, String");
+                }
+
+                @Override
+                public Scalar read(JsonReader in) throws IOException {
+                    Object deserialized = null;
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    int match = 0;
+                    ArrayList<String> errorMessages = new ArrayList<>();
+                    TypeAdapter actualAdapter = elementAdapter;
+
+                    // deserialize String
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      if(!jsonElement.getAsJsonPrimitive().isString()) {
+                        throw new IllegalArgumentException(String.format("Expected json element to be of type String in the JSON string but got `%s`", jsonElement.toString()));
+                      }
+                      actualAdapter = adapterString;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'String'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for String failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'String'", e);
+                    }
+                    // deserialize BigDecimal
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      if(!jsonElement.getAsJsonPrimitive().isNumber()) {
+                        throw new IllegalArgumentException(String.format("Expected json element to be of type Number in the JSON string but got `%s`", jsonElement.toString()));
+                      }
+                      actualAdapter = adapterBigDecimal;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'BigDecimal'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for BigDecimal failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'BigDecimal'", e);
+                    }
+                    // deserialize Boolean
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      if(!jsonElement.getAsJsonPrimitive().isBoolean()) {
+                        throw new IllegalArgumentException(String.format("Expected json element to be of type Boolean in the JSON string but got `%s`", jsonElement.toString()));
+                      }
+                      actualAdapter = adapterBoolean;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Boolean'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Boolean failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Boolean'", e);
+                    }
+
+                    if (match == 1) {
+                        Scalar ret = new Scalar();
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
+                        return ret;
+                    }
+
+                    throw new IOException(String.format("Failed deserialization for Scalar: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
+                }
+            }.nullSafe();
+        }
+    }
+
+    // store a list of schema names defined in oneOf
+    public static final Map<String, Class<?>> schemas = new HashMap<String, Class<?>>();
+
+    public Scalar() {
+        super("oneOf", Boolean.FALSE);
+    }
+
+    public Scalar(BigDecimal o) {
+        super("oneOf", Boolean.FALSE);
+        setActualInstance(o);
+    }
+
+    public Scalar(Boolean o) {
+        super("oneOf", Boolean.FALSE);
+        setActualInstance(o);
+    }
+
+    public Scalar(String o) {
+        super("oneOf", Boolean.FALSE);
+        setActualInstance(o);
+    }
+
+    static {
+        schemas.put("String", String.class);
+        schemas.put("BigDecimal", BigDecimal.class);
+        schemas.put("Boolean", Boolean.class);
+    }
+
+    @Override
+    public Map<String, Class<?>> getSchemas() {
+        return Scalar.schemas;
+    }
+
+    /**
+     * Set the instance that matches the oneOf child schema, check
+     * the instance parameter is valid against the oneOf child schemas:
+     * BigDecimal, Boolean, String
+     *
+     * It could be an instance of the 'oneOf' schemas.
+     * The oneOf child schemas may themselves be a composed schema (allOf, anyOf, oneOf).
+     */
+    @Override
+    public void setActualInstance(Object instance) {
+        if (instance instanceof String) {
+            super.setActualInstance(instance);
+            return;
+        }
+
+        if (instance instanceof BigDecimal) {
+            super.setActualInstance(instance);
+            return;
+        }
+
+        if (instance instanceof Boolean) {
+            super.setActualInstance(instance);
+            return;
+        }
+
+        throw new RuntimeException("Invalid instance type. Must be BigDecimal, Boolean, String");
+    }
+
+    /**
+     * Get the actual instance, which can be the following:
+     * BigDecimal, Boolean, String
+     *
+     * @return The actual instance (BigDecimal, Boolean, String)
+     */
+    @Override
+    public Object getActualInstance() {
+        return super.getActualInstance();
+    }
+
+    /**
+     * Get the actual instance of `String`. If the actual instance is not `String`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `String`
+     * @throws ClassCastException if the instance is not `String`
+     */
+    public String getString() throws ClassCastException {
+        return (String)super.getActualInstance();
+    }
+    /**
+     * Get the actual instance of `BigDecimal`. If the actual instance is not `BigDecimal`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `BigDecimal`
+     * @throws ClassCastException if the instance is not `BigDecimal`
+     */
+    public BigDecimal getBigDecimal() throws ClassCastException {
+        return (BigDecimal)super.getActualInstance();
+    }
+    /**
+     * Get the actual instance of `Boolean`. If the actual instance is not `Boolean`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `Boolean`
+     * @throws ClassCastException if the instance is not `Boolean`
+     */
+    public Boolean getBoolean() throws ClassCastException {
+        return (Boolean)super.getActualInstance();
+    }
+
+ /**
+  * Validates the JSON Element and throws an exception if issues found
+  *
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Scalar
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+    // validate oneOf schemas one by one
+    int validCount = 0;
+    ArrayList<String> errorMessages = new ArrayList<>();
+    // validate the json string with String
+    try {
+      if(!jsonElement.getAsJsonPrimitive().isString()) {
+        throw new IllegalArgumentException(String.format("Expected json element to be of type String in the JSON string but got `%s`", jsonElement.toString()));
+      }
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for String failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
+    // validate the json string with BigDecimal
+    try {
+      if(!jsonElement.getAsJsonPrimitive().isNumber()) {
+        throw new IllegalArgumentException(String.format("Expected json element to be of type Number in the JSON string but got `%s`", jsonElement.toString()));
+      }
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for BigDecimal failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
+    // validate the json string with Boolean
+    try {
+      if(!jsonElement.getAsJsonPrimitive().isBoolean()) {
+        throw new IllegalArgumentException(String.format("Expected json element to be of type Boolean in the JSON string but got `%s`", jsonElement.toString()));
+      }
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for Boolean failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
+    if (validCount != 1) {
+      throw new IOException(String.format("The JSON string is invalid for Scalar with oneOf schemas: BigDecimal, Boolean, String. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
+    }
+  }
+
+ /**
+  * Create an instance of Scalar given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of Scalar
+  * @throws IOException if the JSON string is invalid with respect to Scalar
+  */
+  public static Scalar fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, Scalar.class);
+  }
+
+ /**
+  * Convert an instance of Scalar to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ScaleneTriangle.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ScaleneTriangle.java
index cbb03c02652..c803ca502dd 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ScaleneTriangle.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ScaleneTriangle.java
@@ -208,24 +208,25 @@ public class ScaleneTriangle {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ScaleneTriangle
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ScaleneTriangle
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ScaleneTriangle.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ScaleneTriangle.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ScaleneTriangle is not found in the empty JSON string", ScaleneTriangle.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : ScaleneTriangle.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("shapeType").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `shapeType` to be a primitive type in the JSON string but got `%s`", jsonObj.get("shapeType").toString()));
       }
@@ -271,8 +272,9 @@ public class ScaleneTriangle {
 
            @Override
            public ScaleneTriangle read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ScaleneTriangle instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Shape.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Shape.java
index b3c56f09676..0773e76bbb2 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Shape.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Shape.java
@@ -34,6 +34,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -53,6 +54,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -69,8 +71,8 @@ public class Shape extends AbstractOpenApiSchema {
                 return null; // this class only serializes 'Shape' and its subtypes
             }
             final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
-            final TypeAdapter<Quadrilateral> adapterQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(Quadrilateral.class));
             final TypeAdapter<Triangle> adapterTriangle = gson.getDelegateAdapter(this, TypeToken.get(Triangle.class));
+            final TypeAdapter<Quadrilateral> adapterQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(Quadrilateral.class));
 
             return (TypeAdapter<T>) new TypeAdapter<Shape>() {
                 @Override
@@ -80,27 +82,27 @@ public class Shape extends AbstractOpenApiSchema {
                         return;
                     }
 
-                    // check if the actual instance is of the type `Quadrilateral`
-                    if (value.getActualInstance() instanceof Quadrilateral) {
-                        JsonObject obj = adapterQuadrilateral.toJsonTree((Quadrilateral)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
-                    }
-
                     // check if the actual instance is of the type `Triangle`
                     if (value.getActualInstance() instanceof Triangle) {
-                        JsonObject obj = adapterTriangle.toJsonTree((Triangle)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterTriangle.toJsonTree((Triangle)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
+                    }
+                    // check if the actual instance is of the type `Quadrilateral`
+                    if (value.getActualInstance() instanceof Quadrilateral) {
+                      JsonElement element = adapterQuadrilateral.toJsonTree((Quadrilateral)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: Quadrilateral, Triangle");
                 }
 
                 @Override
                 public Shape read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    JsonObject jsonObject = jsonElement.getAsJsonObject();
 
                     // use discriminator value for faster oneOf lookup
                     Shape newShape = new Shape();
@@ -126,39 +128,38 @@ public class Shape extends AbstractOpenApiSchema {
                     ArrayList<String> errorMessages = new ArrayList<>();
                     TypeAdapter actualAdapter = elementAdapter;
 
-                    // deserialize Quadrilateral
-                    try {
-                        // validate the JSON object to see if any exception is thrown
-                        Quadrilateral.validateJsonObject(jsonObject);
-                        actualAdapter = adapterQuadrilateral;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Quadrilateral'");
-                    } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Quadrilateral'", e);
-                    }
-
                     // deserialize Triangle
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        Triangle.validateJsonObject(jsonObject);
-                        actualAdapter = adapterTriangle;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Triangle'");
+                      // validate the JSON object to see if any exception is thrown
+                      Triangle.validateJsonElement(jsonElement);
+                      actualAdapter = adapterTriangle;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Triangle'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Triangle'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Triangle'", e);
+                    }
+                    // deserialize Quadrilateral
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      Quadrilateral.validateJsonElement(jsonElement);
+                      actualAdapter = adapterQuadrilateral;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Quadrilateral'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Quadrilateral'", e);
                     }
 
                     if (match == 1) {
                         Shape ret = new Shape();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for Shape: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for Shape: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -182,8 +183,8 @@ public class Shape extends AbstractOpenApiSchema {
     }
 
     static {
-        schemas.put("Quadrilateral", Quadrilateral.class);
         schemas.put("Triangle", Triangle.class);
+        schemas.put("Quadrilateral", Quadrilateral.class);
     }
 
     @Override
@@ -201,12 +202,12 @@ public class Shape extends AbstractOpenApiSchema {
      */
     @Override
     public void setActualInstance(Object instance) {
-        if (instance instanceof Quadrilateral) {
+        if (instance instanceof Triangle) {
             super.setActualInstance(instance);
             return;
         }
 
-        if (instance instanceof Triangle) {
+        if (instance instanceof Quadrilateral) {
             super.setActualInstance(instance);
             return;
         }
@@ -225,6 +226,16 @@ public class Shape extends AbstractOpenApiSchema {
         return super.getActualInstance();
     }
 
+    /**
+     * Get the actual instance of `Triangle`. If the actual instance is not `Triangle`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `Triangle`
+     * @throws ClassCastException if the instance is not `Triangle`
+     */
+    public Triangle getTriangle() throws ClassCastException {
+        return (Triangle)super.getActualInstance();
+    }
     /**
      * Get the actual instance of `Quadrilateral`. If the actual instance is not `Quadrilateral`,
      * the ClassCastException will be thrown.
@@ -236,46 +247,34 @@ public class Shape extends AbstractOpenApiSchema {
         return (Quadrilateral)super.getActualInstance();
     }
 
-    /**
-     * Get the actual instance of `Triangle`. If the actual instance is not `Triangle`,
-     * the ClassCastException will be thrown.
-     *
-     * @return The actual instance of `Triangle`
-     * @throws ClassCastException if the instance is not `Triangle`
-     */
-    public Triangle getTriangle() throws ClassCastException {
-        return (Triangle)super.getActualInstance();
-    }
-
-
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Shape
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Shape
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
-    // validate the json string with Quadrilateral
-    try {
-      Quadrilateral.validateJsonObject(jsonObj);
-      validCount++;
-    } catch (Exception e) {
-      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
-      // continue to the next one
-    }
     // validate the json string with Triangle
     try {
-      Triangle.validateJsonObject(jsonObj);
+      Triangle.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
+    // validate the json string with Quadrilateral
+    try {
+      Quadrilateral.validateJsonElement(jsonElement);
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for Shape with oneOf schemas: Quadrilateral, Triangle. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for Shape with oneOf schemas: Quadrilateral, Triangle. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeInterface.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeInterface.java
index 0a70d056506..97247f30d55 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeInterface.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeInterface.java
@@ -179,24 +179,25 @@ public class ShapeInterface {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ShapeInterface
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ShapeInterface
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!ShapeInterface.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ShapeInterface.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in ShapeInterface is not found in the empty JSON string", ShapeInterface.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : ShapeInterface.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("shapeType").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `shapeType` to be a primitive type in the JSON string but got `%s`", jsonObj.get("shapeType").toString()));
       }
@@ -239,8 +240,9 @@ public class ShapeInterface {
 
            @Override
            public ShapeInterface read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              ShapeInterface instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeOrNull.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeOrNull.java
index 1e1689e4874..964c6590fad 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeOrNull.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeOrNull.java
@@ -34,6 +34,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -53,6 +54,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -69,8 +71,8 @@ public class ShapeOrNull extends AbstractOpenApiSchema {
                 return null; // this class only serializes 'ShapeOrNull' and its subtypes
             }
             final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
-            final TypeAdapter<Quadrilateral> adapterQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(Quadrilateral.class));
             final TypeAdapter<Triangle> adapterTriangle = gson.getDelegateAdapter(this, TypeToken.get(Triangle.class));
+            final TypeAdapter<Quadrilateral> adapterQuadrilateral = gson.getDelegateAdapter(this, TypeToken.get(Quadrilateral.class));
 
             return (TypeAdapter<T>) new TypeAdapter<ShapeOrNull>() {
                 @Override
@@ -80,27 +82,27 @@ public class ShapeOrNull extends AbstractOpenApiSchema {
                         return;
                     }
 
-                    // check if the actual instance is of the type `Quadrilateral`
-                    if (value.getActualInstance() instanceof Quadrilateral) {
-                        JsonObject obj = adapterQuadrilateral.toJsonTree((Quadrilateral)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
-                    }
-
                     // check if the actual instance is of the type `Triangle`
                     if (value.getActualInstance() instanceof Triangle) {
-                        JsonObject obj = adapterTriangle.toJsonTree((Triangle)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterTriangle.toJsonTree((Triangle)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
+                    }
+                    // check if the actual instance is of the type `Quadrilateral`
+                    if (value.getActualInstance() instanceof Quadrilateral) {
+                      JsonElement element = adapterQuadrilateral.toJsonTree((Quadrilateral)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: Quadrilateral, Triangle");
                 }
 
                 @Override
                 public ShapeOrNull read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    JsonObject jsonObject = jsonElement.getAsJsonObject();
 
                     // use discriminator value for faster oneOf lookup
                     ShapeOrNull newShapeOrNull = new ShapeOrNull();
@@ -126,39 +128,38 @@ public class ShapeOrNull extends AbstractOpenApiSchema {
                     ArrayList<String> errorMessages = new ArrayList<>();
                     TypeAdapter actualAdapter = elementAdapter;
 
-                    // deserialize Quadrilateral
-                    try {
-                        // validate the JSON object to see if any exception is thrown
-                        Quadrilateral.validateJsonObject(jsonObject);
-                        actualAdapter = adapterQuadrilateral;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Quadrilateral'");
-                    } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Quadrilateral'", e);
-                    }
-
                     // deserialize Triangle
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        Triangle.validateJsonObject(jsonObject);
-                        actualAdapter = adapterTriangle;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'Triangle'");
+                      // validate the JSON object to see if any exception is thrown
+                      Triangle.validateJsonElement(jsonElement);
+                      actualAdapter = adapterTriangle;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Triangle'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'Triangle'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Triangle'", e);
+                    }
+                    // deserialize Quadrilateral
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      Quadrilateral.validateJsonElement(jsonElement);
+                      actualAdapter = adapterQuadrilateral;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Quadrilateral'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Quadrilateral'", e);
                     }
 
                     if (match == 1) {
                         ShapeOrNull ret = new ShapeOrNull();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for ShapeOrNull: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for ShapeOrNull: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -182,8 +183,8 @@ public class ShapeOrNull extends AbstractOpenApiSchema {
     }
 
     static {
-        schemas.put("Quadrilateral", Quadrilateral.class);
         schemas.put("Triangle", Triangle.class);
+        schemas.put("Quadrilateral", Quadrilateral.class);
     }
 
     @Override
@@ -206,12 +207,12 @@ public class ShapeOrNull extends AbstractOpenApiSchema {
            return;
         }
 
-        if (instance instanceof Quadrilateral) {
+        if (instance instanceof Triangle) {
             super.setActualInstance(instance);
             return;
         }
 
-        if (instance instanceof Triangle) {
+        if (instance instanceof Quadrilateral) {
             super.setActualInstance(instance);
             return;
         }
@@ -230,6 +231,16 @@ public class ShapeOrNull extends AbstractOpenApiSchema {
         return super.getActualInstance();
     }
 
+    /**
+     * Get the actual instance of `Triangle`. If the actual instance is not `Triangle`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `Triangle`
+     * @throws ClassCastException if the instance is not `Triangle`
+     */
+    public Triangle getTriangle() throws ClassCastException {
+        return (Triangle)super.getActualInstance();
+    }
     /**
      * Get the actual instance of `Quadrilateral`. If the actual instance is not `Quadrilateral`,
      * the ClassCastException will be thrown.
@@ -241,46 +252,34 @@ public class ShapeOrNull extends AbstractOpenApiSchema {
         return (Quadrilateral)super.getActualInstance();
     }
 
-    /**
-     * Get the actual instance of `Triangle`. If the actual instance is not `Triangle`,
-     * the ClassCastException will be thrown.
-     *
-     * @return The actual instance of `Triangle`
-     * @throws ClassCastException if the instance is not `Triangle`
-     */
-    public Triangle getTriangle() throws ClassCastException {
-        return (Triangle)super.getActualInstance();
-    }
-
-
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to ShapeOrNull
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to ShapeOrNull
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
-    // validate the json string with Quadrilateral
-    try {
-      Quadrilateral.validateJsonObject(jsonObj);
-      validCount++;
-    } catch (Exception e) {
-      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
-      // continue to the next one
-    }
     // validate the json string with Triangle
     try {
-      Triangle.validateJsonObject(jsonObj);
+      Triangle.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for Triangle failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
+    // validate the json string with Quadrilateral
+    try {
+      Quadrilateral.validateJsonElement(jsonElement);
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for Quadrilateral failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for ShapeOrNull with oneOf schemas: Quadrilateral, Triangle. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for ShapeOrNull with oneOf schemas: Quadrilateral, Triangle. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/SimpleQuadrilateral.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/SimpleQuadrilateral.java
index 5b76557d2a9..05a8336e6e1 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/SimpleQuadrilateral.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/SimpleQuadrilateral.java
@@ -208,24 +208,25 @@ public class SimpleQuadrilateral {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to SimpleQuadrilateral
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to SimpleQuadrilateral
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!SimpleQuadrilateral.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!SimpleQuadrilateral.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in SimpleQuadrilateral is not found in the empty JSON string", SimpleQuadrilateral.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : SimpleQuadrilateral.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("shapeType").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `shapeType` to be a primitive type in the JSON string but got `%s`", jsonObj.get("shapeType").toString()));
       }
@@ -271,8 +272,9 @@ public class SimpleQuadrilateral {
 
            @Override
            public SimpleQuadrilateral read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              SimpleQuadrilateral instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/SpecialModelName.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/SpecialModelName.java
index f374028b7a4..afc8d407d9f 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/SpecialModelName.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/SpecialModelName.java
@@ -206,17 +206,18 @@ public class SpecialModelName {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to SpecialModelName
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to SpecialModelName
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!SpecialModelName.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!SpecialModelName.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in SpecialModelName is not found in the empty JSON string", SpecialModelName.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("_special_model.name_") != null && !jsonObj.get("_special_model.name_").isJsonNull()) && !jsonObj.get("_special_model.name_").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `_special_model.name_` to be a primitive type in the JSON string but got `%s`", jsonObj.get("_special_model.name_").toString()));
       }
@@ -259,8 +260,9 @@ public class SpecialModelName {
 
            @Override
            public SpecialModelName read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              SpecialModelName instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Tag.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Tag.java
index 766f1192c86..5523397dcc3 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Tag.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Tag.java
@@ -206,17 +206,18 @@ public class Tag {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Tag
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Tag
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Tag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Tag is not found in the empty JSON string", Tag.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("name") != null && !jsonObj.get("name").isJsonNull()) && !jsonObj.get("name").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
       }
@@ -259,8 +260,9 @@ public class Tag {
 
            @Override
            public Tag read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Tag instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Triangle.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Triangle.java
index d6205f068b9..07ce9117d0f 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Triangle.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Triangle.java
@@ -35,6 +35,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import com.google.gson.Gson;
@@ -54,6 +55,7 @@ import com.google.gson.JsonSerializationContext;
 import com.google.gson.JsonSerializer;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonParseException;
 
 import org.openapitools.client.JSON;
@@ -84,32 +86,31 @@ public class Triangle extends AbstractOpenApiSchema {
 
                     // check if the actual instance is of the type `EquilateralTriangle`
                     if (value.getActualInstance() instanceof EquilateralTriangle) {
-                        JsonObject obj = adapterEquilateralTriangle.toJsonTree((EquilateralTriangle)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterEquilateralTriangle.toJsonTree((EquilateralTriangle)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     // check if the actual instance is of the type `IsoscelesTriangle`
                     if (value.getActualInstance() instanceof IsoscelesTriangle) {
-                        JsonObject obj = adapterIsoscelesTriangle.toJsonTree((IsoscelesTriangle)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterIsoscelesTriangle.toJsonTree((IsoscelesTriangle)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     // check if the actual instance is of the type `ScaleneTriangle`
                     if (value.getActualInstance() instanceof ScaleneTriangle) {
-                        JsonObject obj = adapterScaleneTriangle.toJsonTree((ScaleneTriangle)value.getActualInstance()).getAsJsonObject();
-                        elementAdapter.write(out, obj);
-                        return;
+                      JsonElement element = adapterScaleneTriangle.toJsonTree((ScaleneTriangle)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
                     }
-
                     throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: EquilateralTriangle, IsoscelesTriangle, ScaleneTriangle");
                 }
 
                 @Override
                 public Triangle read(JsonReader in) throws IOException {
                     Object deserialized = null;
-                    JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    JsonObject jsonObject = jsonElement.getAsJsonObject();
 
                     // use discriminator value for faster oneOf lookup
                     Triangle newTriangle = new Triangle();
@@ -141,50 +142,48 @@ public class Triangle extends AbstractOpenApiSchema {
 
                     // deserialize EquilateralTriangle
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        EquilateralTriangle.validateJsonObject(jsonObject);
-                        actualAdapter = adapterEquilateralTriangle;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'EquilateralTriangle'");
+                      // validate the JSON object to see if any exception is thrown
+                      EquilateralTriangle.validateJsonElement(jsonElement);
+                      actualAdapter = adapterEquilateralTriangle;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'EquilateralTriangle'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for EquilateralTriangle failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'EquilateralTriangle'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for EquilateralTriangle failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'EquilateralTriangle'", e);
                     }
-
                     // deserialize IsoscelesTriangle
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        IsoscelesTriangle.validateJsonObject(jsonObject);
-                        actualAdapter = adapterIsoscelesTriangle;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'IsoscelesTriangle'");
+                      // validate the JSON object to see if any exception is thrown
+                      IsoscelesTriangle.validateJsonElement(jsonElement);
+                      actualAdapter = adapterIsoscelesTriangle;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'IsoscelesTriangle'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for IsoscelesTriangle failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'IsoscelesTriangle'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for IsoscelesTriangle failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'IsoscelesTriangle'", e);
                     }
-
                     // deserialize ScaleneTriangle
                     try {
-                        // validate the JSON object to see if any exception is thrown
-                        ScaleneTriangle.validateJsonObject(jsonObject);
-                        actualAdapter = adapterScaleneTriangle;
-                        match++;
-                        log.log(Level.FINER, "Input data matches schema 'ScaleneTriangle'");
+                      // validate the JSON object to see if any exception is thrown
+                      ScaleneTriangle.validateJsonElement(jsonElement);
+                      actualAdapter = adapterScaleneTriangle;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'ScaleneTriangle'");
                     } catch (Exception e) {
-                        // deserialization failed, continue
-                        errorMessages.add(String.format("Deserialization for ScaleneTriangle failed with `%s`.", e.getMessage()));
-                        log.log(Level.FINER, "Input data does not match schema 'ScaleneTriangle'", e);
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for ScaleneTriangle failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'ScaleneTriangle'", e);
                     }
 
                     if (match == 1) {
                         Triangle ret = new Triangle();
-                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonObject));
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
                         return ret;
                     }
 
-                    throw new IOException(String.format("Failed deserialization for Triangle: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonObject.toString()));
+                    throw new IOException(String.format("Failed deserialization for Triangle: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
                 }
             }.nullSafe();
         }
@@ -272,7 +271,6 @@ public class Triangle extends AbstractOpenApiSchema {
     public EquilateralTriangle getEquilateralTriangle() throws ClassCastException {
         return (EquilateralTriangle)super.getActualInstance();
     }
-
     /**
      * Get the actual instance of `IsoscelesTriangle`. If the actual instance is not `IsoscelesTriangle`,
      * the ClassCastException will be thrown.
@@ -283,7 +281,6 @@ public class Triangle extends AbstractOpenApiSchema {
     public IsoscelesTriangle getIsoscelesTriangle() throws ClassCastException {
         return (IsoscelesTriangle)super.getActualInstance();
     }
-
     /**
      * Get the actual instance of `ScaleneTriangle`. If the actual instance is not `ScaleneTriangle`,
      * the ClassCastException will be thrown.
@@ -295,20 +292,19 @@ public class Triangle extends AbstractOpenApiSchema {
         return (ScaleneTriangle)super.getActualInstance();
     }
 
-
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Triangle
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Triangle
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
     // validate oneOf schemas one by one
     int validCount = 0;
     ArrayList<String> errorMessages = new ArrayList<>();
     // validate the json string with EquilateralTriangle
     try {
-      EquilateralTriangle.validateJsonObject(jsonObj);
+      EquilateralTriangle.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for EquilateralTriangle failed with `%s`.", e.getMessage()));
@@ -316,7 +312,7 @@ public class Triangle extends AbstractOpenApiSchema {
     }
     // validate the json string with IsoscelesTriangle
     try {
-      IsoscelesTriangle.validateJsonObject(jsonObj);
+      IsoscelesTriangle.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for IsoscelesTriangle failed with `%s`.", e.getMessage()));
@@ -324,14 +320,14 @@ public class Triangle extends AbstractOpenApiSchema {
     }
     // validate the json string with ScaleneTriangle
     try {
-      ScaleneTriangle.validateJsonObject(jsonObj);
+      ScaleneTriangle.validateJsonElement(jsonElement);
       validCount++;
     } catch (Exception e) {
       errorMessages.add(String.format("Deserialization for ScaleneTriangle failed with `%s`.", e.getMessage()));
       // continue to the next one
     }
     if (validCount != 1) {
-      throw new IOException(String.format("The JSON string is invalid for Triangle with oneOf schemas: EquilateralTriangle, IsoscelesTriangle, ScaleneTriangle. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonObj.toString()));
+      throw new IOException(String.format("The JSON string is invalid for Triangle with oneOf schemas: EquilateralTriangle, IsoscelesTriangle, ScaleneTriangle. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
     }
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/TriangleInterface.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/TriangleInterface.java
index a5fe18ef8be..1598caeed33 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/TriangleInterface.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/TriangleInterface.java
@@ -179,24 +179,25 @@ public class TriangleInterface {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to TriangleInterface
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to TriangleInterface
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!TriangleInterface.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!TriangleInterface.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in TriangleInterface is not found in the empty JSON string", TriangleInterface.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : TriangleInterface.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("triangleType").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `triangleType` to be a primitive type in the JSON string but got `%s`", jsonObj.get("triangleType").toString()));
       }
@@ -239,8 +240,9 @@ public class TriangleInterface {
 
            @Override
            public TriangleInterface read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              TriangleInterface instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/User.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/User.java
index 69b36b6ec87..4ee67296b22 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/User.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/User.java
@@ -498,17 +498,18 @@ public class User {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to User
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to User
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!User.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in User is not found in the empty JSON string", User.openapiRequiredFields.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("username") != null && !jsonObj.get("username").isJsonNull()) && !jsonObj.get("username").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `username` to be a primitive type in the JSON string but got `%s`", jsonObj.get("username").toString()));
       }
@@ -566,8 +567,9 @@ public class User {
 
            @Override
            public User read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              User instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Value.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Value.java
new file mode 100644
index 00000000000..5e4ddd08ced
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Value.java
@@ -0,0 +1,295 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import java.util.Objects;
+import java.util.Arrays;
+import org.openapitools.client.model.Scalar;
+
+
+
+import java.io.IOException;
+import java.lang.reflect.Type;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParseException;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.JsonPrimitive;
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.annotations.SerializedName;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonParseException;
+
+import org.openapitools.client.JSON;
+
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
+public class Value extends AbstractOpenApiSchema {
+    private static final Logger log = Logger.getLogger(Value.class.getName());
+
+    public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+        @SuppressWarnings("unchecked")
+        @Override
+        public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+            if (!Value.class.isAssignableFrom(type.getRawType())) {
+                return null; // this class only serializes 'Value' and its subtypes
+            }
+            final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+            final TypeAdapter<Scalar> adapterScalar = gson.getDelegateAdapter(this, TypeToken.get(Scalar.class));
+
+            final Type typeInstance = new TypeToken<List<Scalar>>(){}.getType();
+            final TypeAdapter<List<Scalar>> adapterScalarList = (TypeAdapter<List<Scalar>>) gson.getDelegateAdapter(this, TypeToken.get(typeInstance));
+
+            return (TypeAdapter<T>) new TypeAdapter<Value>() {
+                @Override
+                public void write(JsonWriter out, Value value) throws IOException {
+                    if (value == null || value.getActualInstance() == null) {
+                        elementAdapter.write(out, null);
+                        return;
+                    }
+
+                    // check if the actual instance is of the type `Scalar`
+                    if (value.getActualInstance() instanceof Scalar) {
+                      JsonElement element = adapterScalar.toJsonTree((Scalar)value.getActualInstance());
+                      elementAdapter.write(out, element);
+                      return;
+                    }
+                    // check if the actual instance is of the type `List<Scalar>`
+                    if (value.getActualInstance() instanceof List<?>) {
+                      List<?> list = (List<?>) value.getActualInstance();
+        	            if(list.get(0) instanceof Scalar) {
+        		            JsonArray array = adapterScalarList.toJsonTree((List<Scalar>)value.getActualInstance()).getAsJsonArray();
+                        elementAdapter.write(out, array);
+                        return;
+        	            }
+                    }
+                    throw new IOException("Failed to serialize as the type doesn't match oneOf schemas: List<Scalar>, Scalar");
+                }
+
+                @Override
+                public Value read(JsonReader in) throws IOException {
+                    Object deserialized = null;
+                    JsonElement jsonElement = elementAdapter.read(in);
+
+                    int match = 0;
+                    ArrayList<String> errorMessages = new ArrayList<>();
+                    TypeAdapter actualAdapter = elementAdapter;
+
+                    // deserialize Scalar
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      Scalar.validateJsonElement(jsonElement);
+                      actualAdapter = adapterScalar;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'Scalar'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for Scalar failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'Scalar'", e);
+                    }
+                    // deserialize List<Scalar>
+                    try {
+                      // validate the JSON object to see if any exception is thrown
+                      if (!jsonElement.isJsonArray()) {
+                        throw new IllegalArgumentException(String.format("Expected json element to be a array type in the JSON string but got `%s`", jsonElement.toString()));
+                      }
+
+                      JsonArray array = jsonElement.getAsJsonArray();
+                      // validate array items
+                      for(JsonElement element : array) {
+                        Scalar.validateJsonElement(element);
+                      }
+                      actualAdapter = adapterScalarList;
+                      match++;
+                      log.log(Level.FINER, "Input data matches schema 'List<Scalar>'");
+                    } catch (Exception e) {
+                      // deserialization failed, continue
+                      errorMessages.add(String.format("Deserialization for List<Scalar> failed with `%s`.", e.getMessage()));
+                      log.log(Level.FINER, "Input data does not match schema 'List<Scalar>'", e);
+                    }
+
+                    if (match == 1) {
+                        Value ret = new Value();
+                        ret.setActualInstance(actualAdapter.fromJsonTree(jsonElement));
+                        return ret;
+                    }
+
+                    throw new IOException(String.format("Failed deserialization for Value: %d classes match result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", match, errorMessages, jsonElement.toString()));
+                }
+            }.nullSafe();
+        }
+    }
+
+    // store a list of schema names defined in oneOf
+    public static final Map<String, Class<?>> schemas = new HashMap<String, Class<?>>();
+
+    public Value() {
+        super("oneOf", Boolean.FALSE);
+    }
+
+    public Value(List<Scalar> o) {
+        super("oneOf", Boolean.FALSE);
+        setActualInstance(o);
+    }
+
+    public Value(Scalar o) {
+        super("oneOf", Boolean.FALSE);
+        setActualInstance(o);
+    }
+
+    static {
+        schemas.put("Scalar", Scalar.class);
+        schemas.put("List<Scalar>", List.class);
+    }
+
+    @Override
+    public Map<String, Class<?>> getSchemas() {
+        return Value.schemas;
+    }
+
+    /**
+     * Set the instance that matches the oneOf child schema, check
+     * the instance parameter is valid against the oneOf child schemas:
+     * List<Scalar>, Scalar
+     *
+     * It could be an instance of the 'oneOf' schemas.
+     * The oneOf child schemas may themselves be a composed schema (allOf, anyOf, oneOf).
+     */
+    @Override
+    public void setActualInstance(Object instance) {
+        if (instance instanceof Scalar) {
+            super.setActualInstance(instance);
+            return;
+        }
+
+        if (instance instanceof List<?>) {
+            List<?> list = (List<?>) instance;
+        	if(list.get(0) instanceof Scalar) {
+        		super.setActualInstance(instance);
+        		return;
+        	}
+        }
+
+        throw new RuntimeException("Invalid instance type. Must be List<Scalar>, Scalar");
+    }
+
+    /**
+     * Get the actual instance, which can be the following:
+     * List<Scalar>, Scalar
+     *
+     * @return The actual instance (List<Scalar>, Scalar)
+     */
+    @Override
+    public Object getActualInstance() {
+        return super.getActualInstance();
+    }
+
+    /**
+     * Get the actual instance of `Scalar`. If the actual instance is not `Scalar`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `Scalar`
+     * @throws ClassCastException if the instance is not `Scalar`
+     */
+    public Scalar getScalar() throws ClassCastException {
+        return (Scalar)super.getActualInstance();
+    }
+    /**
+     * Get the actual instance of `List<Scalar>`. If the actual instance is not `List<Scalar>`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `List<Scalar>`
+     * @throws ClassCastException if the instance is not `List<Scalar>`
+     */
+    public List<Scalar> getScalarList() throws ClassCastException {
+        return (List<Scalar>)super.getActualInstance();
+    }
+
+ /**
+  * Validates the JSON Element and throws an exception if issues found
+  *
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Value
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+    // validate oneOf schemas one by one
+    int validCount = 0;
+    ArrayList<String> errorMessages = new ArrayList<>();
+    // validate the json string with Scalar
+    try {
+      Scalar.validateJsonElement(jsonElement);
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for Scalar failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
+    // validate the json string with List<Scalar>
+    try {
+      if (!jsonElement.isJsonArray()) {
+          throw new IllegalArgumentException(String.format("Expected json element to be a array type in the JSON string but got `%s`", jsonElement.toString()));
+      }
+      JsonArray array = jsonElement.getAsJsonArray();
+      // validate array items
+      for(JsonElement element : array) {
+        Scalar.validateJsonElement(element);
+      }
+      validCount++;
+    } catch (Exception e) {
+      errorMessages.add(String.format("Deserialization for List<Scalar> failed with `%s`.", e.getMessage()));
+      // continue to the next one
+    }
+    if (validCount != 1) {
+      throw new IOException(String.format("The JSON string is invalid for Value with oneOf schemas: List<Scalar>, Scalar. %d class(es) match the result, expected 1. Detailed failure message for oneOf schemas: %s. JSON: %s", validCount, errorMessages, jsonElement.toString()));
+    }
+  }
+
+ /**
+  * Create an instance of Value given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of Value
+  * @throws IOException if the JSON string is invalid with respect to Value
+  */
+  public static Value fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, Value.class);
+  }
+
+ /**
+  * Convert an instance of Value to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Variable.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Variable.java
new file mode 100644
index 00000000000..3b8eb69d9f9
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Variable.java
@@ -0,0 +1,325 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import java.util.Objects;
+import java.util.Arrays;
+import com.google.gson.TypeAdapter;
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.annotations.SerializedName;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import org.openapitools.client.model.Value;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+
+import java.lang.reflect.Type;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
+import org.openapitools.client.JSON;
+
+/**
+ * Value object
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
+public class Variable {
+  public static final String SERIALIZED_NAME_NAME = "name";
+  @SerializedName(SERIALIZED_NAME_NAME)
+  private String name;
+
+  public static final String SERIALIZED_NAME_VALUE = "value";
+  @SerializedName(SERIALIZED_NAME_VALUE)
+  private Value value;
+
+  public Variable() {
+  }
+
+  public Variable name(String name) {
+    
+    this.name = name;
+    return this;
+  }
+
+   /**
+   * Get name
+   * @return name
+  **/
+  @javax.annotation.Nonnull
+  public String getName() {
+    return name;
+  }
+
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+
+  public Variable value(Value value) {
+    
+    this.value = value;
+    return this;
+  }
+
+   /**
+   * Get value
+   * @return value
+  **/
+  @javax.annotation.Nonnull
+  public Value getValue() {
+    return value;
+  }
+
+
+  public void setValue(Value value) {
+    this.value = value;
+  }
+
+  /**
+   * A container for additional, undeclared properties.
+   * This is a holder for any undeclared properties as specified with
+   * the 'additionalProperties' keyword in the OAS document.
+   */
+  private Map<String, Object> additionalProperties;
+
+  /**
+   * Set the additional (undeclared) property with the specified name and value.
+   * If the property does not already exist, create it otherwise replace it.
+   *
+   * @param key name of the property
+   * @param value value of the property
+   * @return the Variable instance itself
+   */
+  public Variable putAdditionalProperty(String key, Object value) {
+    if (this.additionalProperties == null) {
+        this.additionalProperties = new HashMap<String, Object>();
+    }
+    this.additionalProperties.put(key, value);
+    return this;
+  }
+
+  /**
+   * Return the additional (undeclared) property.
+   *
+   * @return a map of objects
+   */
+  public Map<String, Object> getAdditionalProperties() {
+    return additionalProperties;
+  }
+
+  /**
+   * Return the additional (undeclared) property with the specified name.
+   *
+   * @param key name of the property
+   * @return an object
+   */
+  public Object getAdditionalProperty(String key) {
+    if (this.additionalProperties == null) {
+        return null;
+    }
+    return this.additionalProperties.get(key);
+  }
+
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    Variable variable = (Variable) o;
+    return Objects.equals(this.name, variable.name) &&
+        Objects.equals(this.value, variable.value)&&
+        Objects.equals(this.additionalProperties, variable.additionalProperties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(name, value, additionalProperties);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class Variable {\n");
+    sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    value: ").append(toIndentedString(value)).append("\n");
+    sb.append("    additionalProperties: ").append(toIndentedString(additionalProperties)).append("\n");
+    sb.append("}");
+    return sb.toString();
+  }
+
+  /**
+   * Convert the given object to string with each line indented by 4 spaces
+   * (except the first line).
+   */
+  private String toIndentedString(Object o) {
+    if (o == null) {
+      return "null";
+    }
+    return o.toString().replace("\n", "\n    ");
+  }
+
+
+  public static HashSet<String> openapiFields;
+  public static HashSet<String> openapiRequiredFields;
+
+  static {
+    // a set of all properties/fields (JSON key names)
+    openapiFields = new HashSet<String>();
+    openapiFields.add("name");
+    openapiFields.add("value");
+
+    // a set of required properties/fields (JSON key names)
+    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields.add("name");
+    openapiRequiredFields.add("value");
+  }
+
+ /**
+  * Validates the JSON Element and throws an exception if issues found
+  *
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Variable
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Variable.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
+          throw new IllegalArgumentException(String.format("The required field(s) %s in Variable is not found in the empty JSON string", Variable.openapiRequiredFields.toString()));
+        }
+      }
+
+      // check to make sure all required properties/fields are present in the JSON string
+      for (String requiredField : Variable.openapiRequiredFields) {
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
+        }
+      }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
+      if (!jsonObj.get("name").isJsonPrimitive()) {
+        throw new IllegalArgumentException(String.format("Expected the field `name` to be a primitive type in the JSON string but got `%s`", jsonObj.get("name").toString()));
+      }
+      // validate the required field `value`
+      Value.validateJsonElement(jsonObj.get("value"));
+  }
+
+  public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+       if (!Variable.class.isAssignableFrom(type.getRawType())) {
+         return null; // this class only serializes 'Variable' and its subtypes
+       }
+       final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+       final TypeAdapter<Variable> thisAdapter
+                        = gson.getDelegateAdapter(this, TypeToken.get(Variable.class));
+
+       return (TypeAdapter<T>) new TypeAdapter<Variable>() {
+           @Override
+           public void write(JsonWriter out, Variable value) throws IOException {
+             JsonObject obj = thisAdapter.toJsonTree(value).getAsJsonObject();
+             obj.remove("additionalProperties");
+             // serialize additional properties
+             if (value.getAdditionalProperties() != null) {
+               for (Map.Entry<String, Object> entry : value.getAdditionalProperties().entrySet()) {
+                 if (entry.getValue() instanceof String)
+                   obj.addProperty(entry.getKey(), (String) entry.getValue());
+                 else if (entry.getValue() instanceof Number)
+                   obj.addProperty(entry.getKey(), (Number) entry.getValue());
+                 else if (entry.getValue() instanceof Boolean)
+                   obj.addProperty(entry.getKey(), (Boolean) entry.getValue());
+                 else if (entry.getValue() instanceof Character)
+                   obj.addProperty(entry.getKey(), (Character) entry.getValue());
+                 else {
+                   obj.add(entry.getKey(), gson.toJsonTree(entry.getValue()).getAsJsonObject());
+                 }
+               }
+             }
+             elementAdapter.write(out, obj);
+           }
+
+           @Override
+           public Variable read(JsonReader in) throws IOException {
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
+             // store additional fields in the deserialized instance
+             Variable instance = thisAdapter.fromJsonTree(jsonObj);
+             for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
+               if (!openapiFields.contains(entry.getKey())) {
+                 if (entry.getValue().isJsonPrimitive()) { // primitive type
+                   if (entry.getValue().getAsJsonPrimitive().isString())
+                     instance.putAdditionalProperty(entry.getKey(), entry.getValue().getAsString());
+                   else if (entry.getValue().getAsJsonPrimitive().isNumber())
+                     instance.putAdditionalProperty(entry.getKey(), entry.getValue().getAsNumber());
+                   else if (entry.getValue().getAsJsonPrimitive().isBoolean())
+                     instance.putAdditionalProperty(entry.getKey(), entry.getValue().getAsBoolean());
+                   else
+                     throw new IllegalArgumentException(String.format("The field `%s` has unknown primitive type. Value: %s", entry.getKey(), entry.getValue().toString()));
+                 } else if (entry.getValue().isJsonArray()) {
+                     instance.putAdditionalProperty(entry.getKey(), gson.fromJson(entry.getValue(), List.class));
+                 } else { // JSON object
+                     instance.putAdditionalProperty(entry.getKey(), gson.fromJson(entry.getValue(), HashMap.class));
+                 }
+               }
+             }
+             return instance;
+           }
+
+       }.nullSafe();
+    }
+  }
+
+ /**
+  * Create an instance of Variable given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of Variable
+  * @throws IOException if the JSON string is invalid with respect to Variable
+  */
+  public static Variable fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, Variable.class);
+  }
+
+ /**
+  * Convert an instance of Variable to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Whale.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Whale.java
index ae95ebd4f81..06d2be32589 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Whale.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Whale.java
@@ -235,24 +235,25 @@ public class Whale {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Whale
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Whale
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Whale.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Whale.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Whale is not found in the empty JSON string", Whale.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Whale.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if (!jsonObj.get("className").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `className` to be a primitive type in the JSON string but got `%s`", jsonObj.get("className").toString()));
       }
@@ -295,8 +296,9 @@ public class Whale {
 
            @Override
            public Whale read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Whale instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Zebra.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Zebra.java
index 7f0d4bc7ea4..207bdf1efd5 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Zebra.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Zebra.java
@@ -256,24 +256,25 @@ public class Zebra {
   }
 
  /**
-  * Validates the JSON Object and throws an exception if issues found
+  * Validates the JSON Element and throws an exception if issues found
   *
-  * @param jsonObj JSON Object
-  * @throws IOException if the JSON Object is invalid with respect to Zebra
+  * @param jsonElement JSON Element
+  * @throws IOException if the JSON Element is invalid with respect to Zebra
   */
-  public static void validateJsonObject(JsonObject jsonObj) throws IOException {
-      if (jsonObj == null) {
-        if (!Zebra.openapiRequiredFields.isEmpty()) { // has required fields but JSON object is null
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!Zebra.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
           throw new IllegalArgumentException(String.format("The required field(s) %s in Zebra is not found in the empty JSON string", Zebra.openapiRequiredFields.toString()));
         }
       }
 
       // check to make sure all required properties/fields are present in the JSON string
       for (String requiredField : Zebra.openapiRequiredFields) {
-        if (jsonObj.get(requiredField) == null) {
-          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonObj.toString()));
+        if (jsonElement.getAsJsonObject().get(requiredField) == null) {
+          throw new IllegalArgumentException(String.format("The required field `%s` is not found in the JSON string: %s", requiredField, jsonElement.toString()));
         }
       }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
       if ((jsonObj.get("type") != null && !jsonObj.get("type").isJsonNull()) && !jsonObj.get("type").isJsonPrimitive()) {
         throw new IllegalArgumentException(String.format("Expected the field `type` to be a primitive type in the JSON string but got `%s`", jsonObj.get("type").toString()));
       }
@@ -319,8 +320,9 @@ public class Zebra {
 
            @Override
            public Zebra read(JsonReader in) throws IOException {
-             JsonObject jsonObj = elementAdapter.read(in).getAsJsonObject();
-             validateJsonObject(jsonObj);
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
              // store additional fields in the deserialized instance
              Zebra instance = thisAdapter.fromJsonTree(jsonObj);
              for (Map.Entry<String, JsonElement> entry : jsonObj.entrySet()) {
diff --git a/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/JSONTest.java b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/JSONTest.java
index f6c6b02786a..491b649c7ee 100644
--- a/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/JSONTest.java
+++ b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/JSONTest.java
@@ -4,11 +4,13 @@ import static org.junit.jupiter.api.Assertions.*;
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.reflect.TypeToken;
 
 import java.io.IOException;
 import java.lang.reflect.Type;
+import java.math.BigDecimal;
 import java.nio.charset.StandardCharsets;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
@@ -22,6 +24,7 @@ import java.util.Date;
 import java.util.GregorianCalendar;
 import java.util.Locale;
 import java.util.TimeZone;
+import java.util.List;
 
 import okio.ByteString;
 import org.junit.jupiter.api.*;
@@ -430,7 +433,7 @@ public class JSONTest {
             Exception exception = assertThrows(com.google.gson.JsonSyntaxException.class, () -> {
                 Mammal o = json.getGson().fromJson(str, Mammal.class);
             });
-            assertEquals("java.io.IOException: Failed deserialization for Mammal: 0 classes match result, expected 1. Detailed failure message for oneOf schemas: [Deserialization for Pig failed with `The JSON string is invalid for Pig with oneOf schemas: BasquePig, DanishPig. 0 class(es) match the result, expected 1. Detailed failure message for oneOf schemas: [Deserialization for BasquePig failed with `The required field `className` is not found in the JSON string: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`., Deserialization for DanishPig failed with `The required field `className` is not found in the JSON string: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`.]. JSON: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`., Deserialization for Whale failed with `The required field `className` is not found in the JSON string: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`., Deserialization for Zebra failed with `The required field `className` is not found in the JSON string: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`.]. JSON: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}", exception.getMessage());
+            assertEquals("java.io.IOException: Failed deserialization for Mammal: 0 classes match result, expected 1. Detailed failure message for oneOf schemas: [Deserialization for Whale failed with `The required field `className` is not found in the JSON string: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`., Deserialization for Zebra failed with `The required field `className` is not found in the JSON string: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`., Deserialization for Pig failed with `The JSON string is invalid for Pig with oneOf schemas: BasquePig, DanishPig. 0 class(es) match the result, expected 1. Detailed failure message for oneOf schemas: [Deserialization for BasquePig failed with `The required field `className` is not found in the JSON string: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`., Deserialization for DanishPig failed with `The required field `className` is not found in the JSON string: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`.]. JSON: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}`.]. JSON: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}", exception.getMessage());
         }
         {
             // Try to deserialize empty object. This should fail 'oneOf' because none will match
@@ -439,7 +442,143 @@ public class JSONTest {
             Exception exception = assertThrows(com.google.gson.JsonSyntaxException.class, () -> {
                 json.getGson().fromJson(str, Mammal.class);
             });
-            assertEquals("java.io.IOException: Failed deserialization for Mammal: 0 classes match result, expected 1. Detailed failure message for oneOf schemas: [Deserialization for Pig failed with `The JSON string is invalid for Pig with oneOf schemas: BasquePig, DanishPig. 0 class(es) match the result, expected 1. Detailed failure message for oneOf schemas: [Deserialization for BasquePig failed with `The required field `className` is not found in the JSON string: {}`., Deserialization for DanishPig failed with `The required field `className` is not found in the JSON string: {}`.]. JSON: {}`., Deserialization for Whale failed with `The required field `className` is not found in the JSON string: {}`., Deserialization for Zebra failed with `The required field `className` is not found in the JSON string: {}`.]. JSON: {}", exception.getMessage());
+            assertEquals("java.io.IOException: Failed deserialization for Mammal: 0 classes match result, expected 1. Detailed failure message for oneOf schemas: [Deserialization for Whale failed with `The required field `className` is not found in the JSON string: {}`., Deserialization for Zebra failed with `The required field `className` is not found in the JSON string: {}`., Deserialization for Pig failed with `The JSON string is invalid for Pig with oneOf schemas: BasquePig, DanishPig. 0 class(es) match the result, expected 1. Detailed failure message for oneOf schemas: [Deserialization for BasquePig failed with `The required field `className` is not found in the JSON string: {}`., Deserialization for DanishPig failed with `The required field `className` is not found in the JSON string: {}`.]. JSON: {}`.]. JSON: {}", exception.getMessage());
+        }
+    }
+
+    /**
+     * Validate a oneOf schema can be deserialized into the expected class.
+     * The oneOf schema contains primitive Types.
+     */
+    @Test
+    public void testOneOfSchemaWithPrimitives() throws Exception {
+        {
+            String str = "{\"name\":\"bool_1\",\"value\":false}";
+
+            Variable variable = json.getGson().fromJson(str, Variable.class);
+            assertEquals(variable.getName(), "bool_1");
+            assertTrue(variable.getValue().getActualInstance() instanceof Scalar);
+
+            Scalar scalar = (Scalar) variable.getValue().getActualInstance();
+            assertTrue(scalar.getActualInstance() instanceof Boolean);
+
+            Boolean value = (Boolean) scalar.getActualInstance();
+            assertEquals(value, false);
+
+            assertEquals(json.getGson().toJson(variable), str);
+        }
+        {
+            String str = "{\"name\":\"string_1\",\"value\":\"string\"}";
+
+            Variable variable = json.getGson().fromJson(str, Variable.class);
+            assertEquals(variable.getName(), "string_1");
+            assertTrue(variable.getValue().getActualInstance() instanceof Scalar);
+
+            Scalar scalar = (Scalar) variable.getValue().getActualInstance();
+            assertTrue(scalar.getActualInstance() instanceof String);
+            
+            String value = (String) scalar.getActualInstance();
+            assertEquals(value, "string");
+
+            assertEquals(json.getGson().toJson(variable), str);
+        }
+        {
+            String str = "{\"name\":\"decimal_1\",\"value\":124567890.0987654321}";
+
+            Variable variable = json.getGson().fromJson(str, Variable.class);
+            assertEquals(variable.getName(), "decimal_1");
+            assertTrue(variable.getValue().getActualInstance() instanceof Scalar);
+
+            Scalar scalar = (Scalar) variable.getValue().getActualInstance();
+            assertTrue(scalar.getActualInstance() instanceof BigDecimal);
+            
+            BigDecimal value = (BigDecimal) scalar.getActualInstance();
+            assertEquals(value, new BigDecimal("124567890.0987654321"));
+
+            assertEquals(json.getGson().toJson(variable), str);
+        }
+    }
+
+    /**
+     * Validate a oneOf schema can be deserialized into the expected class.
+     * The oneOf schema contains an array with elements of primitive types.
+     */
+    @Test
+    public void testOneofSchemaWithArrayOfPrimitives() throws Exception {
+        {
+            String str = "{\"name\":\"bool_array_1\",\"value\":[false,true,false]}";
+
+            Variable variable = json.getGson().fromJson(str, Variable.class);
+            assertEquals(variable.getName(), "bool_array_1");
+            assertTrue(variable.getValue().getActualInstance() instanceof List<?>);
+
+            List<Scalar> list = (List<Scalar>) variable.getValue().getActualInstance();
+            Scalar item_0 = list.get(0);
+            Scalar item_1 = list.get(1);
+            Scalar item_2 = list.get(2);
+
+            assertTrue(item_0.getActualInstance() instanceof Boolean);
+            assertTrue(item_1.getActualInstance() instanceof Boolean);
+            assertTrue(item_2.getActualInstance() instanceof Boolean);
+
+            Boolean bool_0 = (Boolean) item_0.getActualInstance();
+            Boolean bool_1 = (Boolean) item_1.getActualInstance();
+            Boolean bool_2 = (Boolean) item_2.getActualInstance();
+            assertEquals(bool_0, false);
+            assertEquals(bool_1, true);
+            assertEquals(bool_2, false);
+
+            assertEquals(json.getGson().toJson(variable), str);
+        }
+        {
+            String str = "{\"name\":\"string_array_1\",\"value\":[\"string_0\",\"string_1\",\"string_2\"]}";
+
+            Variable variable = json.getGson().fromJson(str, Variable.class);
+            assertEquals(variable.getName(), "string_array_1");
+            assertTrue(variable.getValue().getActualInstance() instanceof List<?>);
+
+            List<Scalar> list = (List<Scalar>) variable.getValue().getActualInstance();
+            Scalar item_0 = list.get(0);
+            Scalar item_1 = list.get(1);
+            Scalar item_2 = list.get(2);
+
+            assertTrue(item_0.getActualInstance() instanceof String);
+            assertTrue(item_1.getActualInstance() instanceof String);
+            assertTrue(item_2.getActualInstance() instanceof String);
+
+            String string_0 = (String) item_0.getActualInstance();
+            String string_1 = (String) item_1.getActualInstance();
+            String string_2 = (String) item_2.getActualInstance();
+            assertEquals(string_0, "string_0");
+            assertEquals(string_1, "string_1");
+            assertEquals(string_2, "string_2");
+
+            assertEquals(json.getGson().toJson(variable), str);
+        }
+        {
+            String str = "{\"name\":\"decimal_array_1\",\"value\":[124567890.0987654321,987654321.123456789,1112222210.2222222211]}";
+
+            Variable variable = json.getGson().fromJson(str, Variable.class);
+            assertEquals(variable.getName(), "decimal_array_1");
+            assertTrue(variable.getValue().getActualInstance() instanceof List<?>);
+
+            List<Scalar> list = (List<Scalar>) variable.getValue().getActualInstance();
+            Scalar item_0 = list.get(0);
+            Scalar item_1 = list.get(1);
+            Scalar item_2 = list.get(2);
+
+            assertTrue(item_0.getActualInstance() instanceof BigDecimal);
+            assertTrue(item_1.getActualInstance() instanceof BigDecimal);
+            assertTrue(item_2.getActualInstance() instanceof BigDecimal);
+
+            BigDecimal decimal_0 = (BigDecimal) item_0.getActualInstance();
+            BigDecimal decimal_1 = (BigDecimal) item_1.getActualInstance();
+            BigDecimal decimal_2 = (BigDecimal) item_2.getActualInstance();
+            assertEquals(decimal_0, new BigDecimal("124567890.0987654321"));
+            assertEquals(decimal_1, new BigDecimal("987654321.123456789"));
+            assertEquals(decimal_2, new BigDecimal("1112222210.2222222211"));
+
+            assertEquals(json.getGson().toJson(variable), str);
         }
     }
 
@@ -547,14 +686,14 @@ public class JSONTest {
 
 
     /**
-     * Test validateJsonObject with null object
+     * Test validateJsonElement with null object
      */
     @Test
-    public void testValidateJsonObject() throws Exception {
-        JsonObject jsonObject = new JsonObject();
+    public void testValidateJsonElement() throws Exception {
+        JsonElement jsonElement = json.getGson().toJsonTree(new JsonObject());
         Exception exception = assertThrows(java.lang.IllegalArgumentException.class, () -> {
-            Pet.validateJsonObject(jsonObject);
-        });
+                Pet.validateJsonElement(jsonElement);
+                });
         assertEquals(exception.getMessage(), "The required field `photoUrls` is not found in the JSON string: {}");
     }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/api/ValuesApiTest.java b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/api/ValuesApiTest.java
new file mode 100644
index 00000000000..89a1ad0febc
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/api/ValuesApiTest.java
@@ -0,0 +1,47 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.api;
+
+import org.openapitools.client.ApiException;
+import org.openapitools.client.model.Variable;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * API tests for ValuesApi
+ */
+@Disabled
+public class ValuesApiTest {
+
+    private final ValuesApi api = new ValuesApi();
+
+    /**
+     * Get some primitive variable values
+     *
+     * 
+     *
+     * @throws ApiException if the Api call fails
+     */
+    @Test
+    public void getSomeValuesTest() throws ApiException {
+        Variable response = api.getSomeValues();
+        // TODO: test validations
+    }
+
+}
diff --git a/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/ScalarTest.java b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/ScalarTest.java
new file mode 100644
index 00000000000..d09367a1ded
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/ScalarTest.java
@@ -0,0 +1,34 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+
+/**
+ * Model tests for Scalar
+ */
+public class ScalarTest {
+    private final Scalar model = new Scalar();
+
+    /**
+     * Model tests for Scalar
+     */
+    @Test
+    public void testScalar() {
+        // TODO: test Scalar
+    }
+
+}
diff --git a/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/ValueTest.java b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/ValueTest.java
new file mode 100644
index 00000000000..641ea73fb26
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/ValueTest.java
@@ -0,0 +1,35 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import org.openapitools.client.model.Scalar;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+
+/**
+ * Model tests for Value
+ */
+public class ValueTest {
+    private final Value model = new Value();
+
+    /**
+     * Model tests for Value
+     */
+    @Test
+    public void testValue() {
+        // TODO: test Value
+    }
+
+}
diff --git a/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/VariableTest.java b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/VariableTest.java
new file mode 100644
index 00000000000..736a08a495a
--- /dev/null
+++ b/samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/VariableTest.java
@@ -0,0 +1,57 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.annotations.SerializedName;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import org.openapitools.client.model.Value;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+
+/**
+ * Model tests for Variable
+ */
+public class VariableTest {
+    private final Variable model = new Variable();
+
+    /**
+     * Model tests for Variable
+     */
+    @Test
+    public void testVariable() {
+        // TODO: test Variable
+    }
+
+    /**
+     * Test the property 'name'
+     */
+    @Test
+    public void nameTest() {
+        // TODO: test name
+    }
+
+    /**
+     * Test the property 'value'
+     */
+    @Test
+    public void valueTest() {
+        // TODO: test value
+    }
+
+}
diff --git a/samples/client/petstore/java/rest-assured-jackson/docs/FakeApi.md b/samples/client/petstore/java/rest-assured-jackson/docs/FakeApi.md
index 969883dc514..b31cdb856dd 100644
--- a/samples/client/petstore/java/rest-assured-jackson/docs/FakeApi.md
+++ b/samples/client/petstore/java/rest-assured-jackson/docs/FakeApi.md
@@ -174,7 +174,7 @@ api.fakeOuterNumberSerialize().execute(r -> r.prettyPeek());
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
index b0531df4da6..2aef2789f96 100644
--- a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
@@ -138,7 +138,6 @@ public class AdditionalPropertiesClass {
    * @return mapNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_MAP_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index 6562c7ce928..1c0e5024381 100644
--- a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -62,7 +62,6 @@ public class ArrayOfNumberOnly {
    * @return arrayNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_ARRAY_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/FormatTest.java b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/FormatTest.java
index 24c613991cf..05c898ac5e6 100644
--- a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/FormatTest.java
+++ b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/FormatTest.java
@@ -197,7 +197,6 @@ public class FormatTest {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
  @DecimalMin("32.1") @DecimalMax("543.2")
   @JsonProperty(JSON_PROPERTY_NUMBER)
   @JsonInclude(value = JsonInclude.Include.ALWAYS)
@@ -479,7 +478,6 @@ public class FormatTest {
    * @return bigDecimal
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_BIG_DECIMAL)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/NumberOnly.java b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/NumberOnly.java
index a15fbfe24cb..45e35946edd 100644
--- a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/NumberOnly.java
+++ b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/NumberOnly.java
@@ -52,7 +52,6 @@ public class NumberOnly {
    * @return justNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_JUST_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/OuterComposite.java b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/OuterComposite.java
index a8d42de2a20..b51d47ef91a 100644
--- a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/OuterComposite.java
+++ b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/OuterComposite.java
@@ -60,7 +60,6 @@ public class OuterComposite {
    * @return myNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_MY_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/TypeHolderDefault.java b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
index cf982c67760..813f36d0c99 100644
--- a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
+++ b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
@@ -99,7 +99,6 @@ public class TypeHolderDefault {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_NUMBER_ITEM)
   @JsonInclude(value = JsonInclude.Include.ALWAYS)
diff --git a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/TypeHolderExample.java b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/TypeHolderExample.java
index a15d332f772..35466a1616d 100644
--- a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/TypeHolderExample.java
+++ b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/TypeHolderExample.java
@@ -103,7 +103,6 @@ public class TypeHolderExample {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_NUMBER_ITEM)
   @JsonInclude(value = JsonInclude.Include.ALWAYS)
diff --git a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/XmlItem.java b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/XmlItem.java
index 6f95936174f..6b0bb61940d 100644
--- a/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/XmlItem.java
+++ b/samples/client/petstore/java/rest-assured-jackson/src/main/java/org/openapitools/client/model/XmlItem.java
@@ -193,7 +193,6 @@ public class XmlItem {
    * @return attributeNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_ATTRIBUTE_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
@@ -337,7 +336,6 @@ public class XmlItem {
    * @return nameNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_NAME_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
@@ -516,7 +514,6 @@ public class XmlItem {
    * @return prefixNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_PREFIX_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
@@ -695,7 +692,6 @@ public class XmlItem {
    * @return namespaceNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_NAMESPACE_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
@@ -874,7 +870,6 @@ public class XmlItem {
    * @return prefixNsNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_PREFIX_NS_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/rest-assured/docs/FakeApi.md b/samples/client/petstore/java/rest-assured/docs/FakeApi.md
index 969883dc514..b31cdb856dd 100644
--- a/samples/client/petstore/java/rest-assured/docs/FakeApi.md
+++ b/samples/client/petstore/java/rest-assured/docs/FakeApi.md
@@ -174,7 +174,7 @@ api.fakeOuterNumberSerialize().execute(r -> r.prettyPeek());
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
index f68ff4f22a9..5c553e4ad51 100644
--- a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
@@ -131,7 +131,6 @@ public class AdditionalPropertiesClass {
    * @return mapNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public Map<String, BigDecimal> getMapNumber() {
diff --git a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index 1ec3840ebb4..d02f155dcd1 100644
--- a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -59,7 +59,6 @@ public class ArrayOfNumberOnly {
    * @return arrayNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public List<BigDecimal> getArrayNumber() {
diff --git a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/FormatTest.java b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/FormatTest.java
index 595f75f15ce..320bf9fdee2 100644
--- a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/FormatTest.java
+++ b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/FormatTest.java
@@ -181,7 +181,6 @@ public class FormatTest {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
  @DecimalMin("32.1") @DecimalMax("543.2")
 
   public BigDecimal getNumber() {
@@ -423,7 +422,6 @@ public class FormatTest {
    * @return bigDecimal
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public BigDecimal getBigDecimal() {
diff --git a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/NumberOnly.java b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/NumberOnly.java
index 8bbbf91359e..8b84049639c 100644
--- a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/NumberOnly.java
+++ b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/NumberOnly.java
@@ -49,7 +49,6 @@ public class NumberOnly {
    * @return justNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public BigDecimal getJustNumber() {
diff --git a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/OuterComposite.java b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/OuterComposite.java
index 58c7274521e..500f546b57e 100644
--- a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/OuterComposite.java
+++ b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/OuterComposite.java
@@ -57,7 +57,6 @@ public class OuterComposite {
    * @return myNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public BigDecimal getMyNumber() {
diff --git a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/TypeHolderDefault.java b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
index d49917fe38f..da172a62be5 100644
--- a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
+++ b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
@@ -92,7 +92,6 @@ public class TypeHolderDefault {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
 
 
   public BigDecimal getNumberItem() {
diff --git a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/TypeHolderExample.java b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/TypeHolderExample.java
index d1586fb3638..2d1111d8eb2 100644
--- a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/TypeHolderExample.java
+++ b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/TypeHolderExample.java
@@ -96,7 +96,6 @@ public class TypeHolderExample {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
 
 
   public BigDecimal getNumberItem() {
diff --git a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/XmlItem.java b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/XmlItem.java
index 9903913048e..135230238f8 100644
--- a/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/XmlItem.java
+++ b/samples/client/petstore/java/rest-assured/src/main/java/org/openapitools/client/model/XmlItem.java
@@ -186,7 +186,6 @@ public class XmlItem {
    * @return attributeNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public BigDecimal getAttributeNumber() {
@@ -310,7 +309,6 @@ public class XmlItem {
    * @return nameNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public BigDecimal getNameNumber() {
@@ -465,7 +463,6 @@ public class XmlItem {
    * @return prefixNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public BigDecimal getPrefixNumber() {
@@ -620,7 +617,6 @@ public class XmlItem {
    * @return namespaceNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public BigDecimal getNamespaceNumber() {
@@ -775,7 +771,6 @@ public class XmlItem {
    * @return prefixNsNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
 
   public BigDecimal getPrefixNsNumber() {
diff --git a/samples/client/petstore/java/resteasy/docs/FakeApi.md b/samples/client/petstore/java/resteasy/docs/FakeApi.md
index 627366e41db..829724b750d 100644
--- a/samples/client/petstore/java/resteasy/docs/FakeApi.md
+++ b/samples/client/petstore/java/resteasy/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/resttemplate-withXml/docs/FakeApi.md b/samples/client/petstore/java/resttemplate-withXml/docs/FakeApi.md
index 627366e41db..829724b750d 100644
--- a/samples/client/petstore/java/resttemplate-withXml/docs/FakeApi.md
+++ b/samples/client/petstore/java/resttemplate-withXml/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/resttemplate/docs/FakeApi.md b/samples/client/petstore/java/resttemplate/docs/FakeApi.md
index 627366e41db..829724b750d 100644
--- a/samples/client/petstore/java/resttemplate/docs/FakeApi.md
+++ b/samples/client/petstore/java/resttemplate/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/retrofit2-play26/docs/FakeApi.md b/samples/client/petstore/java/retrofit2-play26/docs/FakeApi.md
index 5722d2acb57..73d37341b96 100644
--- a/samples/client/petstore/java/retrofit2-play26/docs/FakeApi.md
+++ b/samples/client/petstore/java/retrofit2-play26/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
index 957897178a4..136143205d4 100644
--- a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
+++ b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/AdditionalPropertiesClass.java
@@ -137,7 +137,6 @@ public class AdditionalPropertiesClass {
    * @return mapNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_MAP_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
index b1b97c48f92..b9dd9dc0799 100644
--- a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
+++ b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/ArrayOfNumberOnly.java
@@ -61,7 +61,6 @@ public class ArrayOfNumberOnly {
    * @return arrayNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_ARRAY_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/FormatTest.java b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/FormatTest.java
index 2b21678a0f3..1095c7ff5b1 100644
--- a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/FormatTest.java
+++ b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/FormatTest.java
@@ -196,7 +196,6 @@ public class FormatTest {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
  @DecimalMin("32.1") @DecimalMax("543.2")
   @JsonProperty(JSON_PROPERTY_NUMBER)
   @JsonInclude(value = JsonInclude.Include.ALWAYS)
@@ -478,7 +477,6 @@ public class FormatTest {
    * @return bigDecimal
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_BIG_DECIMAL)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/NumberOnly.java b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/NumberOnly.java
index 33ce4f21fc4..2e30da5f0d4 100644
--- a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/NumberOnly.java
+++ b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/NumberOnly.java
@@ -51,7 +51,6 @@ public class NumberOnly {
    * @return justNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_JUST_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/OuterComposite.java b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/OuterComposite.java
index 7c0884d9428..9a6269c4f08 100644
--- a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/OuterComposite.java
+++ b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/OuterComposite.java
@@ -59,7 +59,6 @@ public class OuterComposite {
    * @return myNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_MY_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/TypeHolderDefault.java b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
index 03857841174..2135c363308 100644
--- a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
+++ b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/TypeHolderDefault.java
@@ -98,7 +98,6 @@ public class TypeHolderDefault {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_NUMBER_ITEM)
   @JsonInclude(value = JsonInclude.Include.ALWAYS)
diff --git a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/TypeHolderExample.java b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/TypeHolderExample.java
index fdfe42fb025..e9b284a576a 100644
--- a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/TypeHolderExample.java
+++ b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/TypeHolderExample.java
@@ -102,7 +102,6 @@ public class TypeHolderExample {
   **/
   @javax.annotation.Nonnull
   @NotNull
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_NUMBER_ITEM)
   @JsonInclude(value = JsonInclude.Include.ALWAYS)
diff --git a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/XmlItem.java b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/XmlItem.java
index 39785f0197e..eda9bbc5799 100644
--- a/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/XmlItem.java
+++ b/samples/client/petstore/java/retrofit2-play26/src/main/java/org/openapitools/client/model/XmlItem.java
@@ -192,7 +192,6 @@ public class XmlItem {
    * @return attributeNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_ATTRIBUTE_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
@@ -336,7 +335,6 @@ public class XmlItem {
    * @return nameNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_NAME_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
@@ -515,7 +513,6 @@ public class XmlItem {
    * @return prefixNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_PREFIX_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
@@ -694,7 +691,6 @@ public class XmlItem {
    * @return namespaceNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_NAMESPACE_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
@@ -873,7 +869,6 @@ public class XmlItem {
    * @return prefixNsNumber
   **/
   @javax.annotation.Nullable
-  @Valid
 
   @JsonProperty(JSON_PROPERTY_PREFIX_NS_NUMBER)
   @JsonInclude(value = JsonInclude.Include.USE_DEFAULTS)
diff --git a/samples/client/petstore/java/retrofit2/docs/FakeApi.md b/samples/client/petstore/java/retrofit2/docs/FakeApi.md
index 5722d2acb57..73d37341b96 100644
--- a/samples/client/petstore/java/retrofit2/docs/FakeApi.md
+++ b/samples/client/petstore/java/retrofit2/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/retrofit2rx2/docs/FakeApi.md b/samples/client/petstore/java/retrofit2rx2/docs/FakeApi.md
index 5722d2acb57..73d37341b96 100644
--- a/samples/client/petstore/java/retrofit2rx2/docs/FakeApi.md
+++ b/samples/client/petstore/java/retrofit2rx2/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/retrofit2rx3/docs/FakeApi.md b/samples/client/petstore/java/retrofit2rx3/docs/FakeApi.md
index 5722d2acb57..73d37341b96 100644
--- a/samples/client/petstore/java/retrofit2rx3/docs/FakeApi.md
+++ b/samples/client/petstore/java/retrofit2rx3/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/vertx-no-nullable/docs/FakeApi.md b/samples/client/petstore/java/vertx-no-nullable/docs/FakeApi.md
index efb255c14f2..1ded2f2e389 100644
--- a/samples/client/petstore/java/vertx-no-nullable/docs/FakeApi.md
+++ b/samples/client/petstore/java/vertx-no-nullable/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/vertx/docs/FakeApi.md b/samples/client/petstore/java/vertx/docs/FakeApi.md
index efb255c14f2..1ded2f2e389 100644
--- a/samples/client/petstore/java/vertx/docs/FakeApi.md
+++ b/samples/client/petstore/java/vertx/docs/FakeApi.md
@@ -266,7 +266,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/webclient-jakarta/docs/FakeApi.md b/samples/client/petstore/java/webclient-jakarta/docs/FakeApi.md
index 6eb12aee357..68b521a0cfe 100644
--- a/samples/client/petstore/java/webclient-jakarta/docs/FakeApi.md
+++ b/samples/client/petstore/java/webclient-jakarta/docs/FakeApi.md
@@ -396,7 +396,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/webclient-swagger2/docs/FakeApi.md b/samples/client/petstore/java/webclient-swagger2/docs/FakeApi.md
index 6eb12aee357..68b521a0cfe 100644
--- a/samples/client/petstore/java/webclient-swagger2/docs/FakeApi.md
+++ b/samples/client/petstore/java/webclient-swagger2/docs/FakeApi.md
@@ -396,7 +396,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/client/petstore/java/webclient/docs/FakeApi.md b/samples/client/petstore/java/webclient/docs/FakeApi.md
index 6eb12aee357..68b521a0cfe 100644
--- a/samples/client/petstore/java/webclient/docs/FakeApi.md
+++ b/samples/client/petstore/java/webclient/docs/FakeApi.md
@@ -396,7 +396,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization
 
diff --git a/samples/openapi3/client/petstore/java/jersey2-java8/docs/FakeApi.md b/samples/openapi3/client/petstore/java/jersey2-java8/docs/FakeApi.md
index 0663bb791e4..2fa172a50ba 100644
--- a/samples/openapi3/client/petstore/java/jersey2-java8/docs/FakeApi.md
+++ b/samples/openapi3/client/petstore/java/jersey2-java8/docs/FakeApi.md
@@ -260,7 +260,7 @@ public class Example {
 
 ### Return type
 
-[**BigDecimal**](BigDecimal.md)
+**BigDecimal**
 
 ### Authorization