[normalizer] fix schemas incorrectly skipped (#18297)

* fix circular reference check in normalizer

* add new files

* fix

modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java

@@ -499,7 +499,7 @@ public class OpenAPINormalizer {
         }
 
         if (StringUtils.isNotEmpty(schema.get$ref())) {
-            // not need to process $ref
+            // no need to process $ref
             return schema;
         }
 
@@ -594,7 +594,7 @@ public class OpenAPINormalizer {
         }
         for (Map.Entry<String, Schema> propertiesEntry : properties.entrySet()) {
             Schema property = propertiesEntry.getValue();
-            Schema newProperty = normalizeSchema(property, visitedSchemas);
+            Schema newProperty = normalizeSchema(property, new HashSet<>());
             propertiesEntry.setValue(newProperty);
         }
     }

modules/openapi-generator/src/test/resources/3_1/java/petstore.yaml

@@ -914,3 +914,33 @@ components:
           description: A list of "good output" node IDs in the prompt.
           items:
             type: string
+    circular_reference_1:
+      type: object
+      properties:
+        prop1:
+          $ref: '#/components/schemas/circular_reference_2'
+    circular_reference_2:
+      type: object
+      properties:
+        prop1:
+          $ref: '#/components/schemas/circular_reference_3'
+    circular_reference_3:
+      type: object
+      properties:
+        prop1:
+          $ref: '#/components/schemas/circular_reference_1'
+    array_of_same_ref:
+      type: object
+      properties:
+        arrayFooOne:
+          type: array
+          items:
+            $ref: '#/components/schemas/Tag'
+        arrayFooTwo:
+          type: array
+          items:
+            $ref: '#/components/schemas/Tag'
+        arrayFooThree:
+          type: array
+          items:
+            $ref: '#/components/schemas/Tag'

samples/client/petstore/java/okhttp-gson-3.1/.openapi-generator/FILES

@@ -8,8 +8,12 @@ build.sbt
 docs/Animal.md
 docs/AnyOfArray.md
 docs/AnyTypeTest.md
+docs/ArrayOfSameRef.md
 docs/Cat.md
 docs/Category.md
+docs/CircularReference1.md
+docs/CircularReference2.md
+docs/CircularReference3.md
 docs/Dog.md
 docs/FakeApi.md
 docs/ModelApiResponse.md
@@ -60,8 +64,12 @@ src/main/java/org/openapitools/client/model/AbstractOpenApiSchema.java
 src/main/java/org/openapitools/client/model/Animal.java
 src/main/java/org/openapitools/client/model/AnyOfArray.java
 src/main/java/org/openapitools/client/model/AnyTypeTest.java
+src/main/java/org/openapitools/client/model/ArrayOfSameRef.java
 src/main/java/org/openapitools/client/model/Cat.java
 src/main/java/org/openapitools/client/model/Category.java
+src/main/java/org/openapitools/client/model/CircularReference1.java
+src/main/java/org/openapitools/client/model/CircularReference2.java
+src/main/java/org/openapitools/client/model/CircularReference3.java
 src/main/java/org/openapitools/client/model/Dog.java
 src/main/java/org/openapitools/client/model/ModelApiResponse.java
 src/main/java/org/openapitools/client/model/OneOfStringOrInt.java

samples/client/petstore/java/okhttp-gson-3.1/README.md

@@ -146,8 +146,12 @@ Class | Method | HTTP request | Description
  - [Animal](docs/Animal.md)
  - [AnyOfArray](docs/AnyOfArray.md)
  - [AnyTypeTest](docs/AnyTypeTest.md)
+ - [ArrayOfSameRef](docs/ArrayOfSameRef.md)
  - [Cat](docs/Cat.md)
  - [Category](docs/Category.md)
+ - [CircularReference1](docs/CircularReference1.md)
+ - [CircularReference2](docs/CircularReference2.md)
+ - [CircularReference3](docs/CircularReference3.md)
  - [Dog](docs/Dog.md)
  - [ModelApiResponse](docs/ModelApiResponse.md)
  - [OneOfStringOrInt](docs/OneOfStringOrInt.md)

samples/client/petstore/java/okhttp-gson-3.1/api/openapi.yaml

@@ -1015,6 +1015,32 @@ components:
       maxItems: 5
       minItems: 3
       type: array
+    circular_reference_1:
+      properties:
+        prop1:
+          $ref: '#/components/schemas/circular_reference_2'
+    circular_reference_2:
+      properties:
+        prop1:
+          $ref: '#/components/schemas/circular_reference_3'
+    circular_reference_3:
+      properties:
+        prop1:
+          $ref: '#/components/schemas/circular_reference_1'
+    array_of_same_ref:
+      properties:
+        arrayFooOne:
+          items:
+            $ref: '#/components/schemas/Tag'
+          type: array
+        arrayFooTwo:
+          items:
+            $ref: '#/components/schemas/Tag'
+          type: array
+        arrayFooThree:
+          items:
+            $ref: '#/components/schemas/Tag'
+          type: array
     updatePetWithForm_request:
       properties:
         name:

samples/client/petstore/java/okhttp-gson-3.1/docs/ArrayOfSameRef.md

@@ -0,0 +1,15 @@
+
+
+# ArrayOfSameRef
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**arrayFooOne** | [**List<Tag>**](Tag.md) |  |  [optional] |
+|**arrayFooTwo** | [**List<Tag>**](Tag.md) |  |  [optional] |
+|**arrayFooThree** | [**List<Tag>**](Tag.md) |  |  [optional] |
+
+
+

samples/client/petstore/java/okhttp-gson-3.1/docs/CircularReference1.md

@@ -0,0 +1,13 @@
+
+
+# CircularReference1
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**prop1** | [**CircularReference2**](CircularReference2.md) |  |  [optional] |
+
+
+

samples/client/petstore/java/okhttp-gson-3.1/docs/CircularReference2.md

@@ -0,0 +1,13 @@
+
+
+# CircularReference2
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**prop1** | [**CircularReference3**](CircularReference3.md) |  |  [optional] |
+
+
+

samples/client/petstore/java/okhttp-gson-3.1/docs/CircularReference3.md

@@ -0,0 +1,13 @@
+
+
+# CircularReference3
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**prop1** | [**CircularReference1**](CircularReference1.md) |  |  [optional] |
+
+
+

samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/JSON.java

@@ -131,8 +131,12 @@ public class JSON {
         gsonBuilder.registerTypeAdapter(byte[].class, byteArrayAdapter);
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.AnyOfArray.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.AnyTypeTest.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.ArrayOfSameRef.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Cat.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Category.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.CircularReference1.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.CircularReference2.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.CircularReference3.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Dog.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.ModelApiResponse.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.OneOfStringOrInt.CustomTypeAdapterFactory());

samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/model/ArrayOfSameRef.java

@@ -0,0 +1,405 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * 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 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 java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import org.openapitools.client.model.Tag;
+
+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.Set;
+
+import org.openapitools.client.JSON;
+
+/**
+ * ArrayOfSameRef
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.5.0-SNAPSHOT")
+public class ArrayOfSameRef {
+  public static final String SERIALIZED_NAME_ARRAY_FOO_ONE = "arrayFooOne";
+  @SerializedName(SERIALIZED_NAME_ARRAY_FOO_ONE)
+  private List<Tag> arrayFooOne = new ArrayList<>();
+
+  public static final String SERIALIZED_NAME_ARRAY_FOO_TWO = "arrayFooTwo";
+  @SerializedName(SERIALIZED_NAME_ARRAY_FOO_TWO)
+  private List<Tag> arrayFooTwo = new ArrayList<>();
+
+  public static final String SERIALIZED_NAME_ARRAY_FOO_THREE = "arrayFooThree";
+  @SerializedName(SERIALIZED_NAME_ARRAY_FOO_THREE)
+  private List<Tag> arrayFooThree = new ArrayList<>();
+
+  public ArrayOfSameRef() {
+  }
+
+  public ArrayOfSameRef arrayFooOne(List<Tag> arrayFooOne) {
+    this.arrayFooOne = arrayFooOne;
+    return this;
+  }
+
+  public ArrayOfSameRef addArrayFooOneItem(Tag arrayFooOneItem) {
+    if (this.arrayFooOne == null) {
+      this.arrayFooOne = new ArrayList<>();
+    }
+    this.arrayFooOne.add(arrayFooOneItem);
+    return this;
+  }
+
+   /**
+   * Get arrayFooOne
+   * @return arrayFooOne
+  **/
+  @javax.annotation.Nullable
+  public List<Tag> getArrayFooOne() {
+    return arrayFooOne;
+  }
+
+  public void setArrayFooOne(List<Tag> arrayFooOne) {
+    this.arrayFooOne = arrayFooOne;
+  }
+
+
+  public ArrayOfSameRef arrayFooTwo(List<Tag> arrayFooTwo) {
+    this.arrayFooTwo = arrayFooTwo;
+    return this;
+  }
+
+  public ArrayOfSameRef addArrayFooTwoItem(Tag arrayFooTwoItem) {
+    if (this.arrayFooTwo == null) {
+      this.arrayFooTwo = new ArrayList<>();
+    }
+    this.arrayFooTwo.add(arrayFooTwoItem);
+    return this;
+  }
+
+   /**
+   * Get arrayFooTwo
+   * @return arrayFooTwo
+  **/
+  @javax.annotation.Nullable
+  public List<Tag> getArrayFooTwo() {
+    return arrayFooTwo;
+  }
+
+  public void setArrayFooTwo(List<Tag> arrayFooTwo) {
+    this.arrayFooTwo = arrayFooTwo;
+  }
+
+
+  public ArrayOfSameRef arrayFooThree(List<Tag> arrayFooThree) {
+    this.arrayFooThree = arrayFooThree;
+    return this;
+  }
+
+  public ArrayOfSameRef addArrayFooThreeItem(Tag arrayFooThreeItem) {
+    if (this.arrayFooThree == null) {
+      this.arrayFooThree = new ArrayList<>();
+    }
+    this.arrayFooThree.add(arrayFooThreeItem);
+    return this;
+  }
+
+   /**
+   * Get arrayFooThree
+   * @return arrayFooThree
+  **/
+  @javax.annotation.Nullable
+  public List<Tag> getArrayFooThree() {
+    return arrayFooThree;
+  }
+
+  public void setArrayFooThree(List<Tag> arrayFooThree) {
+    this.arrayFooThree = arrayFooThree;
+  }
+
+  /**
+   * 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 ArrayOfSameRef instance itself
+   */
+  public ArrayOfSameRef 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;
+    }
+    ArrayOfSameRef arrayOfSameRef = (ArrayOfSameRef) o;
+    return Objects.equals(this.arrayFooOne, arrayOfSameRef.arrayFooOne) &&
+        Objects.equals(this.arrayFooTwo, arrayOfSameRef.arrayFooTwo) &&
+        Objects.equals(this.arrayFooThree, arrayOfSameRef.arrayFooThree)&&
+        Objects.equals(this.additionalProperties, arrayOfSameRef.additionalProperties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(arrayFooOne, arrayFooTwo, arrayFooThree, additionalProperties);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class ArrayOfSameRef {\n");
+    sb.append("    arrayFooOne: ").append(toIndentedString(arrayFooOne)).append("\n");
+    sb.append("    arrayFooTwo: ").append(toIndentedString(arrayFooTwo)).append("\n");
+    sb.append("    arrayFooThree: ").append(toIndentedString(arrayFooThree)).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("arrayFooOne");
+    openapiFields.add("arrayFooTwo");
+    openapiFields.add("arrayFooThree");
+
+    // a set of required properties/fields (JSON key names)
+    openapiRequiredFields = new HashSet<String>();
+  }
+
+ /**
+  * 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 ArrayOfSameRef
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!ArrayOfSameRef.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
+          throw new IllegalArgumentException(String.format("The required field(s) %s in ArrayOfSameRef is not found in the empty JSON string", ArrayOfSameRef.openapiRequiredFields.toString()));
+        }
+      }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
+      if (jsonObj.get("arrayFooOne") != null && !jsonObj.get("arrayFooOne").isJsonNull()) {
+        JsonArray jsonArrayarrayFooOne = jsonObj.getAsJsonArray("arrayFooOne");
+        if (jsonArrayarrayFooOne != null) {
+          // ensure the json data is an array
+          if (!jsonObj.get("arrayFooOne").isJsonArray()) {
+            throw new IllegalArgumentException(String.format("Expected the field `arrayFooOne` to be an array in the JSON string but got `%s`", jsonObj.get("arrayFooOne").toString()));
+          }
+
+          // validate the optional field `arrayFooOne` (array)
+          for (int i = 0; i < jsonArrayarrayFooOne.size(); i++) {
+            Tag.validateJsonElement(jsonArrayarrayFooOne.get(i));
+          };
+        }
+      }
+      if (jsonObj.get("arrayFooTwo") != null && !jsonObj.get("arrayFooTwo").isJsonNull()) {
+        JsonArray jsonArrayarrayFooTwo = jsonObj.getAsJsonArray("arrayFooTwo");
+        if (jsonArrayarrayFooTwo != null) {
+          // ensure the json data is an array
+          if (!jsonObj.get("arrayFooTwo").isJsonArray()) {
+            throw new IllegalArgumentException(String.format("Expected the field `arrayFooTwo` to be an array in the JSON string but got `%s`", jsonObj.get("arrayFooTwo").toString()));
+          }
+
+          // validate the optional field `arrayFooTwo` (array)
+          for (int i = 0; i < jsonArrayarrayFooTwo.size(); i++) {
+            Tag.validateJsonElement(jsonArrayarrayFooTwo.get(i));
+          };
+        }
+      }
+      if (jsonObj.get("arrayFooThree") != null && !jsonObj.get("arrayFooThree").isJsonNull()) {
+        JsonArray jsonArrayarrayFooThree = jsonObj.getAsJsonArray("arrayFooThree");
+        if (jsonArrayarrayFooThree != null) {
+          // ensure the json data is an array
+          if (!jsonObj.get("arrayFooThree").isJsonArray()) {
+            throw new IllegalArgumentException(String.format("Expected the field `arrayFooThree` to be an array in the JSON string but got `%s`", jsonObj.get("arrayFooThree").toString()));
+          }
+
+          // validate the optional field `arrayFooThree` (array)
+          for (int i = 0; i < jsonArrayarrayFooThree.size(); i++) {
+            Tag.validateJsonElement(jsonArrayarrayFooThree.get(i));
+          };
+        }
+      }
+  }
+
+  public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+       if (!ArrayOfSameRef.class.isAssignableFrom(type.getRawType())) {
+         return null; // this class only serializes 'ArrayOfSameRef' and its subtypes
+       }
+       final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+       final TypeAdapter<ArrayOfSameRef> thisAdapter
+                        = gson.getDelegateAdapter(this, TypeToken.get(ArrayOfSameRef.class));
+
+       return (TypeAdapter<T>) new TypeAdapter<ArrayOfSameRef>() {
+           @Override
+           public void write(JsonWriter out, ArrayOfSameRef 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 {
+                   JsonElement jsonElement = gson.toJsonTree(entry.getValue());
+                   if (jsonElement.isJsonArray()) {
+                     obj.add(entry.getKey(), jsonElement.getAsJsonArray());
+                   } else {
+                     obj.add(entry.getKey(), jsonElement.getAsJsonObject());
+                   }
+                 }
+               }
+             }
+             elementAdapter.write(out, obj);
+           }
+
+           @Override
+           public ArrayOfSameRef read(JsonReader in) throws IOException {
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
+             // store additional fields in the deserialized instance
+             ArrayOfSameRef 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 ArrayOfSameRef given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of ArrayOfSameRef
+  * @throws IOException if the JSON string is invalid with respect to ArrayOfSameRef
+  */
+  public static ArrayOfSameRef fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, ArrayOfSameRef.class);
+  }
+
+ /**
+  * Convert an instance of ArrayOfSameRef to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+

samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/model/CircularReference1.java

@@ -0,0 +1,289 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * 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 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 java.util.Arrays;
+import org.openapitools.client.model.CircularReference2;
+
+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.Set;
+
+import org.openapitools.client.JSON;
+
+/**
+ * CircularReference1
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.5.0-SNAPSHOT")
+public class CircularReference1 {
+  public static final String SERIALIZED_NAME_PROP1 = "prop1";
+  @SerializedName(SERIALIZED_NAME_PROP1)
+  private CircularReference2 prop1;
+
+  public CircularReference1() {
+  }
+
+  public CircularReference1 prop1(CircularReference2 prop1) {
+    this.prop1 = prop1;
+    return this;
+  }
+
+   /**
+   * Get prop1
+   * @return prop1
+  **/
+  @javax.annotation.Nullable
+  public CircularReference2 getProp1() {
+    return prop1;
+  }
+
+  public void setProp1(CircularReference2 prop1) {
+    this.prop1 = prop1;
+  }
+
+  /**
+   * 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 CircularReference1 instance itself
+   */
+  public CircularReference1 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;
+    }
+    CircularReference1 circularReference1 = (CircularReference1) o;
+    return Objects.equals(this.prop1, circularReference1.prop1)&&
+        Objects.equals(this.additionalProperties, circularReference1.additionalProperties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(prop1, additionalProperties);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class CircularReference1 {\n");
+    sb.append("    prop1: ").append(toIndentedString(prop1)).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("prop1");
+
+    // a set of required properties/fields (JSON key names)
+    openapiRequiredFields = new HashSet<String>();
+  }
+
+ /**
+  * 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 CircularReference1
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!CircularReference1.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
+          throw new IllegalArgumentException(String.format("The required field(s) %s in CircularReference1 is not found in the empty JSON string", CircularReference1.openapiRequiredFields.toString()));
+        }
+      }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
+      // validate the optional field `prop1`
+      if (jsonObj.get("prop1") != null && !jsonObj.get("prop1").isJsonNull()) {
+        CircularReference2.validateJsonElement(jsonObj.get("prop1"));
+      }
+  }
+
+  public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+       if (!CircularReference1.class.isAssignableFrom(type.getRawType())) {
+         return null; // this class only serializes 'CircularReference1' and its subtypes
+       }
+       final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+       final TypeAdapter<CircularReference1> thisAdapter
+                        = gson.getDelegateAdapter(this, TypeToken.get(CircularReference1.class));
+
+       return (TypeAdapter<T>) new TypeAdapter<CircularReference1>() {
+           @Override
+           public void write(JsonWriter out, CircularReference1 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 {
+                   JsonElement jsonElement = gson.toJsonTree(entry.getValue());
+                   if (jsonElement.isJsonArray()) {
+                     obj.add(entry.getKey(), jsonElement.getAsJsonArray());
+                   } else {
+                     obj.add(entry.getKey(), jsonElement.getAsJsonObject());
+                   }
+                 }
+               }
+             }
+             elementAdapter.write(out, obj);
+           }
+
+           @Override
+           public CircularReference1 read(JsonReader in) throws IOException {
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
+             // store additional fields in the deserialized instance
+             CircularReference1 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 CircularReference1 given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of CircularReference1
+  * @throws IOException if the JSON string is invalid with respect to CircularReference1
+  */
+  public static CircularReference1 fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, CircularReference1.class);
+  }
+
+ /**
+  * Convert an instance of CircularReference1 to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+

samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/model/CircularReference2.java

@@ -0,0 +1,289 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * 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 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 java.util.Arrays;
+import org.openapitools.client.model.CircularReference3;
+
+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.Set;
+
+import org.openapitools.client.JSON;
+
+/**
+ * CircularReference2
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.5.0-SNAPSHOT")
+public class CircularReference2 {
+  public static final String SERIALIZED_NAME_PROP1 = "prop1";
+  @SerializedName(SERIALIZED_NAME_PROP1)
+  private CircularReference3 prop1;
+
+  public CircularReference2() {
+  }
+
+  public CircularReference2 prop1(CircularReference3 prop1) {
+    this.prop1 = prop1;
+    return this;
+  }
+
+   /**
+   * Get prop1
+   * @return prop1
+  **/
+  @javax.annotation.Nullable
+  public CircularReference3 getProp1() {
+    return prop1;
+  }
+
+  public void setProp1(CircularReference3 prop1) {
+    this.prop1 = prop1;
+  }
+
+  /**
+   * 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 CircularReference2 instance itself
+   */
+  public CircularReference2 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;
+    }
+    CircularReference2 circularReference2 = (CircularReference2) o;
+    return Objects.equals(this.prop1, circularReference2.prop1)&&
+        Objects.equals(this.additionalProperties, circularReference2.additionalProperties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(prop1, additionalProperties);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class CircularReference2 {\n");
+    sb.append("    prop1: ").append(toIndentedString(prop1)).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("prop1");
+
+    // a set of required properties/fields (JSON key names)
+    openapiRequiredFields = new HashSet<String>();
+  }
+
+ /**
+  * 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 CircularReference2
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!CircularReference2.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
+          throw new IllegalArgumentException(String.format("The required field(s) %s in CircularReference2 is not found in the empty JSON string", CircularReference2.openapiRequiredFields.toString()));
+        }
+      }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
+      // validate the optional field `prop1`
+      if (jsonObj.get("prop1") != null && !jsonObj.get("prop1").isJsonNull()) {
+        CircularReference3.validateJsonElement(jsonObj.get("prop1"));
+      }
+  }
+
+  public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+       if (!CircularReference2.class.isAssignableFrom(type.getRawType())) {
+         return null; // this class only serializes 'CircularReference2' and its subtypes
+       }
+       final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+       final TypeAdapter<CircularReference2> thisAdapter
+                        = gson.getDelegateAdapter(this, TypeToken.get(CircularReference2.class));
+
+       return (TypeAdapter<T>) new TypeAdapter<CircularReference2>() {
+           @Override
+           public void write(JsonWriter out, CircularReference2 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 {
+                   JsonElement jsonElement = gson.toJsonTree(entry.getValue());
+                   if (jsonElement.isJsonArray()) {
+                     obj.add(entry.getKey(), jsonElement.getAsJsonArray());
+                   } else {
+                     obj.add(entry.getKey(), jsonElement.getAsJsonObject());
+                   }
+                 }
+               }
+             }
+             elementAdapter.write(out, obj);
+           }
+
+           @Override
+           public CircularReference2 read(JsonReader in) throws IOException {
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
+             // store additional fields in the deserialized instance
+             CircularReference2 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 CircularReference2 given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of CircularReference2
+  * @throws IOException if the JSON string is invalid with respect to CircularReference2
+  */
+  public static CircularReference2 fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, CircularReference2.class);
+  }
+
+ /**
+  * Convert an instance of CircularReference2 to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+

samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/model/CircularReference3.java

@@ -0,0 +1,289 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * 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 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 java.util.Arrays;
+import org.openapitools.client.model.CircularReference1;
+
+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.Set;
+
+import org.openapitools.client.JSON;
+
+/**
+ * CircularReference3
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.5.0-SNAPSHOT")
+public class CircularReference3 {
+  public static final String SERIALIZED_NAME_PROP1 = "prop1";
+  @SerializedName(SERIALIZED_NAME_PROP1)
+  private CircularReference1 prop1;
+
+  public CircularReference3() {
+  }
+
+  public CircularReference3 prop1(CircularReference1 prop1) {
+    this.prop1 = prop1;
+    return this;
+  }
+
+   /**
+   * Get prop1
+   * @return prop1
+  **/
+  @javax.annotation.Nullable
+  public CircularReference1 getProp1() {
+    return prop1;
+  }
+
+  public void setProp1(CircularReference1 prop1) {
+    this.prop1 = prop1;
+  }
+
+  /**
+   * 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 CircularReference3 instance itself
+   */
+  public CircularReference3 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;
+    }
+    CircularReference3 circularReference3 = (CircularReference3) o;
+    return Objects.equals(this.prop1, circularReference3.prop1)&&
+        Objects.equals(this.additionalProperties, circularReference3.additionalProperties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(prop1, additionalProperties);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class CircularReference3 {\n");
+    sb.append("    prop1: ").append(toIndentedString(prop1)).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("prop1");
+
+    // a set of required properties/fields (JSON key names)
+    openapiRequiredFields = new HashSet<String>();
+  }
+
+ /**
+  * 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 CircularReference3
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!CircularReference3.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
+          throw new IllegalArgumentException(String.format("The required field(s) %s in CircularReference3 is not found in the empty JSON string", CircularReference3.openapiRequiredFields.toString()));
+        }
+      }
+        JsonObject jsonObj = jsonElement.getAsJsonObject();
+      // validate the optional field `prop1`
+      if (jsonObj.get("prop1") != null && !jsonObj.get("prop1").isJsonNull()) {
+        CircularReference1.validateJsonElement(jsonObj.get("prop1"));
+      }
+  }
+
+  public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+       if (!CircularReference3.class.isAssignableFrom(type.getRawType())) {
+         return null; // this class only serializes 'CircularReference3' and its subtypes
+       }
+       final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+       final TypeAdapter<CircularReference3> thisAdapter
+                        = gson.getDelegateAdapter(this, TypeToken.get(CircularReference3.class));
+
+       return (TypeAdapter<T>) new TypeAdapter<CircularReference3>() {
+           @Override
+           public void write(JsonWriter out, CircularReference3 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 {
+                   JsonElement jsonElement = gson.toJsonTree(entry.getValue());
+                   if (jsonElement.isJsonArray()) {
+                     obj.add(entry.getKey(), jsonElement.getAsJsonArray());
+                   } else {
+                     obj.add(entry.getKey(), jsonElement.getAsJsonObject());
+                   }
+                 }
+               }
+             }
+             elementAdapter.write(out, obj);
+           }
+
+           @Override
+           public CircularReference3 read(JsonReader in) throws IOException {
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
+             // store additional fields in the deserialized instance
+             CircularReference3 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 CircularReference3 given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of CircularReference3
+  * @throws IOException if the JSON string is invalid with respect to CircularReference3
+  */
+  public static CircularReference3 fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, CircularReference3.class);
+  }
+
+ /**
+  * Convert an instance of CircularReference3 to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+

samples/client/petstore/java/okhttp-gson-3.1/src/test/java/org/openapitools/client/model/ArrayOfSameRefTest.java

@@ -0,0 +1,67 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * 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 java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import org.openapitools.client.model.Tag;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for ArrayOfSameRef
+ */
+public class ArrayOfSameRefTest {
+    private final ArrayOfSameRef model = new ArrayOfSameRef();
+
+    /**
+     * Model tests for ArrayOfSameRef
+     */
+    @Test
+    public void testArrayOfSameRef() {
+        // TODO: test ArrayOfSameRef
+    }
+
+    /**
+     * Test the property 'arrayFooOne'
+     */
+    @Test
+    public void arrayFooOneTest() {
+        // TODO: test arrayFooOne
+    }
+
+    /**
+     * Test the property 'arrayFooTwo'
+     */
+    @Test
+    public void arrayFooTwoTest() {
+        // TODO: test arrayFooTwo
+    }
+
+    /**
+     * Test the property 'arrayFooThree'
+     */
+    @Test
+    public void arrayFooThreeTest() {
+        // TODO: test arrayFooThree
+    }
+
+}

samples/client/petstore/java/okhttp-gson-3.1/src/test/java/org/openapitools/client/model/CircularReference1Test.java

@@ -0,0 +1,49 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * 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 java.util.Arrays;
+import org.openapitools.client.model.CircularReference2;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for CircularReference1
+ */
+public class CircularReference1Test {
+    private final CircularReference1 model = new CircularReference1();
+
+    /**
+     * Model tests for CircularReference1
+     */
+    @Test
+    public void testCircularReference1() {
+        // TODO: test CircularReference1
+    }
+
+    /**
+     * Test the property 'prop1'
+     */
+    @Test
+    public void prop1Test() {
+        // TODO: test prop1
+    }
+
+}

samples/client/petstore/java/okhttp-gson-3.1/src/test/java/org/openapitools/client/model/CircularReference2Test.java

@@ -0,0 +1,49 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * 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 java.util.Arrays;
+import org.openapitools.client.model.CircularReference3;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for CircularReference2
+ */
+public class CircularReference2Test {
+    private final CircularReference2 model = new CircularReference2();
+
+    /**
+     * Model tests for CircularReference2
+     */
+    @Test
+    public void testCircularReference2() {
+        // TODO: test CircularReference2
+    }
+
+    /**
+     * Test the property 'prop1'
+     */
+    @Test
+    public void prop1Test() {
+        // TODO: test prop1
+    }
+
+}

samples/client/petstore/java/okhttp-gson-3.1/src/test/java/org/openapitools/client/model/CircularReference3Test.java

@@ -0,0 +1,49 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * 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 java.util.Arrays;
+import org.openapitools.client.model.CircularReference1;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for CircularReference3
+ */
+public class CircularReference3Test {
+    private final CircularReference3 model = new CircularReference3();
+
+    /**
+     * Model tests for CircularReference3
+     */
+    @Test
+    public void testCircularReference3() {
+        // TODO: test CircularReference3
+    }
+
+    /**
+     * Test the property 'prop1'
+     */
+    @Test
+    public void prop1Test() {
+        // TODO: test prop1
+    }
+
+}

w

@@ -0,0 +1,51 @@
+openapi: 3.1.0
+info:
+  title: ""
+  version: ""
+
+paths:
+  /user/getInfo:
+    get:
+      operationId: getUserInfo
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Bar'
+          description: |
+            OK
+      security:
+        - Session: []
+      x-accepts: application/json
+
+components:
+  schemas:
+    Foo:
+      type: object
+      required:
+        - arrayOfStrings
+      properties:
+        arrayOfStrings:
+          type: array
+          items:
+            type: string
+
+    Bar:
+      allOf:
+        - $ref: '#/components/schemas/Foo'
+    Hello:
+      type: object
+      properties:
+        arrayFooOne:
+          type: array
+          items:
+            $ref: '#/components/schemas/Foo'
+        arrayFooTwo:
+          type: array
+          items:
+            $ref: '#/components/schemas/Foo'
+        arrayFooThree:
+          type: array
+          items:
+            $ref: '#/components/schemas/Foo'