Fix allOf with a single $ref (#16096)

* new test

* fix allOf with a single ref in inline model resolver

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

@@ -30,6 +30,7 @@ import io.swagger.v3.oas.models.parameters.Parameter;
 import io.swagger.v3.oas.models.parameters.RequestBody;
 import io.swagger.v3.oas.models.responses.ApiResponse;
 import io.swagger.v3.oas.models.responses.ApiResponses;
+import org.apache.commons.lang3.StringUtils;
 import org.openapitools.codegen.utils.ModelUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -232,6 +233,9 @@ public class InlineModelResolver {
                 if (m.equals(c)) {
                     return isModelNeeded(m.getAllOf().get(0), visitedSchemas);
                 }
+            } else if (isSingleAllOf && StringUtils.isNotEmpty(m.getAllOf().get(0).get$ref())) {
+                // single allOf and it's a ref
+                return isModelNeeded(m.getAllOf().get(0), visitedSchemas);
             }
 
             if (m.getAllOf() != null && !m.getAllOf().isEmpty()) {

modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml

@@ -2268,3 +2268,61 @@ components:
       minItems: 1
       items:
         $ref: '#/components/schemas/Scalar'
+    NewPet:
+      type: object
+      required:
+        - name
+        - photoUrls
+      properties:
+        id:
+          type: integer
+          format: int64
+          x-is-unique: true
+        category_inline_allof:
+          allOf:
+            - type: object
+              required:
+                - name
+              properties:
+                id:
+                  type: integer
+                  format: int64
+                name:
+                  type: string
+                  default: default-name
+                category_tag:
+                  type: object
+                  properties:
+                    id:
+                      type: integer
+                      format: int64
+                    name:
+                      type: string
+        category_allOf_ref:
+          allOf:
+            - $ref: '#/components/schemas/Category'
+        name:
+          type: string
+          example: doggie
+        photoUrls:
+          type: array
+          xml:
+            name: photoUrl
+            wrapped: true
+          items:
+            type: string
+        tags:
+          type: array
+          xml:
+            name: tag
+            wrapped: true
+          items:
+            allOf:
+              - $ref: '#/components/schemas/Tag'
+        status:
+          type: string
+          description: pet status in the store
+          enum:
+            - available
+            - pending
+            - sold

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

@@ -57,6 +57,9 @@ docs/ModelFile.md
 docs/ModelList.md
 docs/ModelReturn.md
 docs/Name.md
+docs/NewPet.md
+docs/NewPetCategoryInlineAllof.md
+docs/NewPetCategoryInlineAllofAllOfCategoryTag.md
 docs/NullableClass.md
 docs/NullableShape.md
 docs/NumberOnly.md
@@ -180,6 +183,9 @@ src/main/java/org/openapitools/client/model/ModelFile.java
 src/main/java/org/openapitools/client/model/ModelList.java
 src/main/java/org/openapitools/client/model/ModelReturn.java
 src/main/java/org/openapitools/client/model/Name.java
+src/main/java/org/openapitools/client/model/NewPet.java
+src/main/java/org/openapitools/client/model/NewPetCategoryInlineAllof.java
+src/main/java/org/openapitools/client/model/NewPetCategoryInlineAllofAllOfCategoryTag.java
 src/main/java/org/openapitools/client/model/NullableClass.java
 src/main/java/org/openapitools/client/model/NullableShape.java
 src/main/java/org/openapitools/client/model/NumberOnly.java

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

@@ -205,6 +205,9 @@ Class | Method | HTTP request | Description
  - [ModelList](docs/ModelList.md)
  - [ModelReturn](docs/ModelReturn.md)
  - [Name](docs/Name.md)
+ - [NewPet](docs/NewPet.md)
+ - [NewPetCategoryInlineAllof](docs/NewPetCategoryInlineAllof.md)
+ - [NewPetCategoryInlineAllofAllOfCategoryTag](docs/NewPetCategoryInlineAllofAllOfCategoryTag.md)
  - [NullableClass](docs/NullableClass.md)
  - [NullableShape](docs/NullableShape.md)
  - [NumberOnly](docs/NumberOnly.md)

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

@@ -2265,6 +2265,46 @@ components:
         $ref: '#/components/schemas/Scalar'
       minItems: 1
       type: array
+    NewPet:
+      properties:
+        id:
+          format: int64
+          type: integer
+          x-is-unique: true
+        category_inline_allof:
+          $ref: '#/components/schemas/NewPet_category_inline_allof'
+        category_allOf_ref:
+          allOf:
+          - $ref: '#/components/schemas/Category'
+        name:
+          example: doggie
+          type: string
+        photoUrls:
+          items:
+            type: string
+          type: array
+          xml:
+            name: photoUrl
+            wrapped: true
+        tags:
+          items:
+            allOf:
+            - $ref: '#/components/schemas/Tag'
+          type: array
+          xml:
+            name: tag
+            wrapped: true
+        status:
+          description: pet status in the store
+          enum:
+          - available
+          - pending
+          - sold
+          type: string
+      required:
+      - name
+      - photoUrls
+      type: object
     _foo_get_default_response:
       example:
         string:
@@ -2420,6 +2460,28 @@ components:
           color:
             type: string
         type: object
+    NewPet_category_inline_allof_allOf_category_tag:
+      properties:
+        id:
+          format: int64
+          type: integer
+        name:
+          type: string
+      type: object
+    NewPet_category_inline_allof:
+      allOf:
+      - properties:
+          id:
+            format: int64
+            type: integer
+          name:
+            default: default-name
+            type: string
+          category_tag:
+            $ref: '#/components/schemas/NewPet_category_inline_allof_allOf_category_tag'
+        required:
+        - name
+        type: object
   securitySchemes:
     petstore_auth:
       flows:

samples/client/petstore/java/okhttp-gson/docs/NewPet.md

@@ -0,0 +1,29 @@
+
+
+# NewPet
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**id** | **Long** |  |  [optional] |
+|**categoryInlineAllof** | [**NewPetCategoryInlineAllof**](NewPetCategoryInlineAllof.md) |  |  [optional] |
+|**categoryAllOfRef** | [**Category**](Category.md) |  |  [optional] |
+|**name** | **String** |  |  |
+|**photoUrls** | **List<String>** |  |  |
+|**tags** | [**List<Tag>**](Tag.md) |  |  [optional] |
+|**status** | [**StatusEnum**](#StatusEnum) | pet status in the store |  [optional] |
+
+
+
+## Enum: StatusEnum
+
+| Name | Value |
+|---- | -----|
+| AVAILABLE | "available" |
+| PENDING | "pending" |
+| SOLD | "sold" |
+
+
+

samples/client/petstore/java/okhttp-gson/docs/NewPetCategoryInlineAllof.md

@@ -0,0 +1,15 @@
+
+
+# NewPetCategoryInlineAllof
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**id** | **Long** |  |  [optional] |
+|**name** | **String** |  |  |
+|**categoryTag** | [**NewPetCategoryInlineAllofAllOfCategoryTag**](NewPetCategoryInlineAllofAllOfCategoryTag.md) |  |  [optional] |
+
+
+

samples/client/petstore/java/okhttp-gson/docs/NewPetCategoryInlineAllofAllOfCategoryTag.md

@@ -0,0 +1,14 @@
+
+
+# NewPetCategoryInlineAllofAllOfCategoryTag
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**id** | **Long** |  |  [optional] |
+|**name** | **String** |  |  [optional] |
+
+
+

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

@@ -274,6 +274,9 @@ public class JSON {
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.ModelList.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.ModelReturn.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Name.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.NewPet.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.NewPetCategoryInlineAllof.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.NewPetCategoryInlineAllofAllOfCategoryTag.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.NullableClass.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.NullableShape.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.NumberOnly.CustomTypeAdapterFactory());

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

@@ -0,0 +1,563 @@
+/*
+ * 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 java.util.ArrayList;
+import java.util.List;
+import org.openapitools.client.model.Category;
+import org.openapitools.client.model.NewPetCategoryInlineAllof;
+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.Map.Entry;
+import java.util.Set;
+
+import org.openapitools.client.JSON;
+
+/**
+ * NewPet
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
+public class NewPet {
+  public static final String SERIALIZED_NAME_ID = "id";
+  @SerializedName(SERIALIZED_NAME_ID)
+  private Long id;
+
+  public static final String SERIALIZED_NAME_CATEGORY_INLINE_ALLOF = "category_inline_allof";
+  @SerializedName(SERIALIZED_NAME_CATEGORY_INLINE_ALLOF)
+  private NewPetCategoryInlineAllof categoryInlineAllof;
+
+  public static final String SERIALIZED_NAME_CATEGORY_ALL_OF_REF = "category_allOf_ref";
+  @SerializedName(SERIALIZED_NAME_CATEGORY_ALL_OF_REF)
+  private Category categoryAllOfRef;
+
+  public static final String SERIALIZED_NAME_NAME = "name";
+  @SerializedName(SERIALIZED_NAME_NAME)
+  private String name;
+
+  public static final String SERIALIZED_NAME_PHOTO_URLS = "photoUrls";
+  @SerializedName(SERIALIZED_NAME_PHOTO_URLS)
+  private List<String> photoUrls = new ArrayList<>();
+
+  public static final String SERIALIZED_NAME_TAGS = "tags";
+  @SerializedName(SERIALIZED_NAME_TAGS)
+  private List<Tag> tags;
+
+  /**
+   * pet status in the store
+   */
+  @JsonAdapter(StatusEnum.Adapter.class)
+  public enum StatusEnum {
+    AVAILABLE("available"),
+    
+    PENDING("pending"),
+    
+    SOLD("sold");
+
+    private String value;
+
+    StatusEnum(String value) {
+      this.value = value;
+    }
+
+    public String getValue() {
+      return value;
+    }
+
+    @Override
+    public String toString() {
+      return String.valueOf(value);
+    }
+
+    public static StatusEnum fromValue(String value) {
+      for (StatusEnum b : StatusEnum.values()) {
+        if (b.value.equals(value)) {
+          return b;
+        }
+      }
+      throw new IllegalArgumentException("Unexpected value '" + value + "'");
+    }
+
+    public static class Adapter extends TypeAdapter<StatusEnum> {
+      @Override
+      public void write(final JsonWriter jsonWriter, final StatusEnum enumeration) throws IOException {
+        jsonWriter.value(enumeration.getValue());
+      }
+
+      @Override
+      public StatusEnum read(final JsonReader jsonReader) throws IOException {
+        String value =  jsonReader.nextString();
+        return StatusEnum.fromValue(value);
+      }
+    }
+  }
+
+  public static final String SERIALIZED_NAME_STATUS = "status";
+  @SerializedName(SERIALIZED_NAME_STATUS)
+  private StatusEnum status;
+
+  public NewPet() {
+  }
+
+  public NewPet id(Long id) {
+    
+    this.id = id;
+    return this;
+  }
+
+   /**
+   * Get id
+   * @return id
+  **/
+  @javax.annotation.Nullable
+  public Long getId() {
+    return id;
+  }
+
+
+  public void setId(Long id) {
+    this.id = id;
+  }
+
+
+  public NewPet categoryInlineAllof(NewPetCategoryInlineAllof categoryInlineAllof) {
+    
+    this.categoryInlineAllof = categoryInlineAllof;
+    return this;
+  }
+
+   /**
+   * Get categoryInlineAllof
+   * @return categoryInlineAllof
+  **/
+  @javax.annotation.Nullable
+  public NewPetCategoryInlineAllof getCategoryInlineAllof() {
+    return categoryInlineAllof;
+  }
+
+
+  public void setCategoryInlineAllof(NewPetCategoryInlineAllof categoryInlineAllof) {
+    this.categoryInlineAllof = categoryInlineAllof;
+  }
+
+
+  public NewPet categoryAllOfRef(Category categoryAllOfRef) {
+    
+    this.categoryAllOfRef = categoryAllOfRef;
+    return this;
+  }
+
+   /**
+   * Get categoryAllOfRef
+   * @return categoryAllOfRef
+  **/
+  @javax.annotation.Nullable
+  public Category getCategoryAllOfRef() {
+    return categoryAllOfRef;
+  }
+
+
+  public void setCategoryAllOfRef(Category categoryAllOfRef) {
+    this.categoryAllOfRef = categoryAllOfRef;
+  }
+
+
+  public NewPet 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 NewPet photoUrls(List<String> photoUrls) {
+    
+    this.photoUrls = photoUrls;
+    return this;
+  }
+
+  public NewPet addPhotoUrlsItem(String photoUrlsItem) {
+    if (this.photoUrls == null) {
+      this.photoUrls = new ArrayList<>();
+    }
+    this.photoUrls.add(photoUrlsItem);
+    return this;
+  }
+
+   /**
+   * Get photoUrls
+   * @return photoUrls
+  **/
+  @javax.annotation.Nonnull
+  public List<String> getPhotoUrls() {
+    return photoUrls;
+  }
+
+
+  public void setPhotoUrls(List<String> photoUrls) {
+    this.photoUrls = photoUrls;
+  }
+
+
+  public NewPet tags(List<Tag> tags) {
+    
+    this.tags = tags;
+    return this;
+  }
+
+  public NewPet addTagsItem(Tag tagsItem) {
+    if (this.tags == null) {
+      this.tags = new ArrayList<>();
+    }
+    this.tags.add(tagsItem);
+    return this;
+  }
+
+   /**
+   * Get tags
+   * @return tags
+  **/
+  @javax.annotation.Nullable
+  public List<Tag> getTags() {
+    return tags;
+  }
+
+
+  public void setTags(List<Tag> tags) {
+    this.tags = tags;
+  }
+
+
+  public NewPet status(StatusEnum status) {
+    
+    this.status = status;
+    return this;
+  }
+
+   /**
+   * pet status in the store
+   * @return status
+  **/
+  @javax.annotation.Nullable
+  public StatusEnum getStatus() {
+    return status;
+  }
+
+
+  public void setStatus(StatusEnum status) {
+    this.status = status;
+  }
+
+  /**
+   * 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 NewPet instance itself
+   */
+  public NewPet 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;
+    }
+    NewPet newPet = (NewPet) o;
+    return Objects.equals(this.id, newPet.id) &&
+        Objects.equals(this.categoryInlineAllof, newPet.categoryInlineAllof) &&
+        Objects.equals(this.categoryAllOfRef, newPet.categoryAllOfRef) &&
+        Objects.equals(this.name, newPet.name) &&
+        Objects.equals(this.photoUrls, newPet.photoUrls) &&
+        Objects.equals(this.tags, newPet.tags) &&
+        Objects.equals(this.status, newPet.status)&&
+        Objects.equals(this.additionalProperties, newPet.additionalProperties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(id, categoryInlineAllof, categoryAllOfRef, name, photoUrls, tags, status, additionalProperties);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class NewPet {\n");
+    sb.append("    id: ").append(toIndentedString(id)).append("\n");
+    sb.append("    categoryInlineAllof: ").append(toIndentedString(categoryInlineAllof)).append("\n");
+    sb.append("    categoryAllOfRef: ").append(toIndentedString(categoryAllOfRef)).append("\n");
+    sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    photoUrls: ").append(toIndentedString(photoUrls)).append("\n");
+    sb.append("    tags: ").append(toIndentedString(tags)).append("\n");
+    sb.append("    status: ").append(toIndentedString(status)).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("id");
+    openapiFields.add("category_inline_allof");
+    openapiFields.add("category_allOf_ref");
+    openapiFields.add("name");
+    openapiFields.add("photoUrls");
+    openapiFields.add("tags");
+    openapiFields.add("status");
+
+    // a set of required properties/fields (JSON key names)
+    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields.add("name");
+    openapiRequiredFields.add("photoUrls");
+  }
+
+ /**
+  * 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 NewPet
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!NewPet.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
+          throw new IllegalArgumentException(String.format("The required field(s) %s in NewPet is not found in the empty JSON string", NewPet.openapiRequiredFields.toString()));
+        }
+      }
+
+      // check to make sure all required properties/fields are present in the JSON string
+      for (String requiredField : NewPet.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();
+      // validate the optional field `category_inline_allof`
+      if (jsonObj.get("category_inline_allof") != null && !jsonObj.get("category_inline_allof").isJsonNull()) {
+        NewPetCategoryInlineAllof.validateJsonElement(jsonObj.get("category_inline_allof"));
+      }
+      // validate the optional field `category_allOf_ref`
+      if (jsonObj.get("category_allOf_ref") != null && !jsonObj.get("category_allOf_ref").isJsonNull()) {
+        Category.validateJsonElement(jsonObj.get("category_allOf_ref"));
+      }
+      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()));
+      }
+      // ensure the required json array is present
+      if (jsonObj.get("photoUrls") == null) {
+        throw new IllegalArgumentException("Expected the field `linkedContent` to be an array in the JSON string but got `null`");
+      } else if (!jsonObj.get("photoUrls").isJsonArray()) {
+        throw new IllegalArgumentException(String.format("Expected the field `photoUrls` to be an array in the JSON string but got `%s`", jsonObj.get("photoUrls").toString()));
+      }
+      if (jsonObj.get("tags") != null && !jsonObj.get("tags").isJsonNull()) {
+        JsonArray jsonArraytags = jsonObj.getAsJsonArray("tags");
+        if (jsonArraytags != null) {
+          // ensure the json data is an array
+          if (!jsonObj.get("tags").isJsonArray()) {
+            throw new IllegalArgumentException(String.format("Expected the field `tags` to be an array in the JSON string but got `%s`", jsonObj.get("tags").toString()));
+          }
+
+          // validate the optional field `tags` (array)
+          for (int i = 0; i < jsonArraytags.size(); i++) {
+            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()));
+      }
+  }
+
+  public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+       if (!NewPet.class.isAssignableFrom(type.getRawType())) {
+         return null; // this class only serializes 'NewPet' and its subtypes
+       }
+       final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+       final TypeAdapter<NewPet> thisAdapter
+                        = gson.getDelegateAdapter(this, TypeToken.get(NewPet.class));
+
+       return (TypeAdapter<T>) new TypeAdapter<NewPet>() {
+           @Override
+           public void write(JsonWriter out, NewPet 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 NewPet read(JsonReader in) throws IOException {
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
+             // store additional fields in the deserialized instance
+             NewPet 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 NewPet given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of NewPet
+  * @throws IOException if the JSON string is invalid with respect to NewPet
+  */
+  public static NewPet fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, NewPet.class);
+  }
+
+ /**
+  * Convert an instance of NewPet to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+

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

@@ -0,0 +1,354 @@
+/*
+ * 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.NewPetCategoryInlineAllofAllOfCategoryTag;
+
+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;
+
+/**
+ * NewPetCategoryInlineAllof
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
+public class NewPetCategoryInlineAllof {
+  public static final String SERIALIZED_NAME_ID = "id";
+  @SerializedName(SERIALIZED_NAME_ID)
+  private Long id;
+
+  public static final String SERIALIZED_NAME_NAME = "name";
+  @SerializedName(SERIALIZED_NAME_NAME)
+  private String name = "default-name";
+
+  public static final String SERIALIZED_NAME_CATEGORY_TAG = "category_tag";
+  @SerializedName(SERIALIZED_NAME_CATEGORY_TAG)
+  private NewPetCategoryInlineAllofAllOfCategoryTag categoryTag;
+
+  public NewPetCategoryInlineAllof() {
+  }
+
+  public NewPetCategoryInlineAllof id(Long id) {
+    
+    this.id = id;
+    return this;
+  }
+
+   /**
+   * Get id
+   * @return id
+  **/
+  @javax.annotation.Nullable
+  public Long getId() {
+    return id;
+  }
+
+
+  public void setId(Long id) {
+    this.id = id;
+  }
+
+
+  public NewPetCategoryInlineAllof 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 NewPetCategoryInlineAllof categoryTag(NewPetCategoryInlineAllofAllOfCategoryTag categoryTag) {
+    
+    this.categoryTag = categoryTag;
+    return this;
+  }
+
+   /**
+   * Get categoryTag
+   * @return categoryTag
+  **/
+  @javax.annotation.Nullable
+  public NewPetCategoryInlineAllofAllOfCategoryTag getCategoryTag() {
+    return categoryTag;
+  }
+
+
+  public void setCategoryTag(NewPetCategoryInlineAllofAllOfCategoryTag categoryTag) {
+    this.categoryTag = categoryTag;
+  }
+
+  /**
+   * 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 NewPetCategoryInlineAllof instance itself
+   */
+  public NewPetCategoryInlineAllof 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;
+    }
+    NewPetCategoryInlineAllof newPetCategoryInlineAllof = (NewPetCategoryInlineAllof) o;
+    return Objects.equals(this.id, newPetCategoryInlineAllof.id) &&
+        Objects.equals(this.name, newPetCategoryInlineAllof.name) &&
+        Objects.equals(this.categoryTag, newPetCategoryInlineAllof.categoryTag)&&
+        Objects.equals(this.additionalProperties, newPetCategoryInlineAllof.additionalProperties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(id, name, categoryTag, additionalProperties);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class NewPetCategoryInlineAllof {\n");
+    sb.append("    id: ").append(toIndentedString(id)).append("\n");
+    sb.append("    name: ").append(toIndentedString(name)).append("\n");
+    sb.append("    categoryTag: ").append(toIndentedString(categoryTag)).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("id");
+    openapiFields.add("name");
+    openapiFields.add("category_tag");
+
+    // a set of required properties/fields (JSON key names)
+    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields.add("name");
+  }
+
+ /**
+  * 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 NewPetCategoryInlineAllof
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!NewPetCategoryInlineAllof.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
+          throw new IllegalArgumentException(String.format("The required field(s) %s in NewPetCategoryInlineAllof is not found in the empty JSON string", NewPetCategoryInlineAllof.openapiRequiredFields.toString()));
+        }
+      }
+
+      // check to make sure all required properties/fields are present in the JSON string
+      for (String requiredField : NewPetCategoryInlineAllof.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 optional field `category_tag`
+      if (jsonObj.get("category_tag") != null && !jsonObj.get("category_tag").isJsonNull()) {
+        NewPetCategoryInlineAllofAllOfCategoryTag.validateJsonElement(jsonObj.get("category_tag"));
+      }
+  }
+
+  public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+       if (!NewPetCategoryInlineAllof.class.isAssignableFrom(type.getRawType())) {
+         return null; // this class only serializes 'NewPetCategoryInlineAllof' and its subtypes
+       }
+       final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+       final TypeAdapter<NewPetCategoryInlineAllof> thisAdapter
+                        = gson.getDelegateAdapter(this, TypeToken.get(NewPetCategoryInlineAllof.class));
+
+       return (TypeAdapter<T>) new TypeAdapter<NewPetCategoryInlineAllof>() {
+           @Override
+           public void write(JsonWriter out, NewPetCategoryInlineAllof 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 NewPetCategoryInlineAllof read(JsonReader in) throws IOException {
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
+             // store additional fields in the deserialized instance
+             NewPetCategoryInlineAllof 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 NewPetCategoryInlineAllof given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of NewPetCategoryInlineAllof
+  * @throws IOException if the JSON string is invalid with respect to NewPetCategoryInlineAllof
+  */
+  public static NewPetCategoryInlineAllof fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, NewPetCategoryInlineAllof.class);
+  }
+
+ /**
+  * Convert an instance of NewPetCategoryInlineAllof to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+

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

@@ -0,0 +1,313 @@
+/*
+ * 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 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;
+
+/**
+ * NewPetCategoryInlineAllofAllOfCategoryTag
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
+public class NewPetCategoryInlineAllofAllOfCategoryTag {
+  public static final String SERIALIZED_NAME_ID = "id";
+  @SerializedName(SERIALIZED_NAME_ID)
+  private Long id;
+
+  public static final String SERIALIZED_NAME_NAME = "name";
+  @SerializedName(SERIALIZED_NAME_NAME)
+  private String name;
+
+  public NewPetCategoryInlineAllofAllOfCategoryTag() {
+  }
+
+  public NewPetCategoryInlineAllofAllOfCategoryTag id(Long id) {
+    
+    this.id = id;
+    return this;
+  }
+
+   /**
+   * Get id
+   * @return id
+  **/
+  @javax.annotation.Nullable
+  public Long getId() {
+    return id;
+  }
+
+
+  public void setId(Long id) {
+    this.id = id;
+  }
+
+
+  public NewPetCategoryInlineAllofAllOfCategoryTag name(String name) {
+    
+    this.name = name;
+    return this;
+  }
+
+   /**
+   * Get name
+   * @return name
+  **/
+  @javax.annotation.Nullable
+  public String getName() {
+    return name;
+  }
+
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  /**
+   * 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 NewPetCategoryInlineAllofAllOfCategoryTag instance itself
+   */
+  public NewPetCategoryInlineAllofAllOfCategoryTag 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;
+    }
+    NewPetCategoryInlineAllofAllOfCategoryTag newPetCategoryInlineAllofAllOfCategoryTag = (NewPetCategoryInlineAllofAllOfCategoryTag) o;
+    return Objects.equals(this.id, newPetCategoryInlineAllofAllOfCategoryTag.id) &&
+        Objects.equals(this.name, newPetCategoryInlineAllofAllOfCategoryTag.name)&&
+        Objects.equals(this.additionalProperties, newPetCategoryInlineAllofAllOfCategoryTag.additionalProperties);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(id, name, additionalProperties);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class NewPetCategoryInlineAllofAllOfCategoryTag {\n");
+    sb.append("    id: ").append(toIndentedString(id)).append("\n");
+    sb.append("    name: ").append(toIndentedString(name)).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("id");
+    openapiFields.add("name");
+
+    // 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 NewPetCategoryInlineAllofAllOfCategoryTag
+  */
+  public static void validateJsonElement(JsonElement jsonElement) throws IOException {
+      if (jsonElement == null) {
+        if (!NewPetCategoryInlineAllofAllOfCategoryTag.openapiRequiredFields.isEmpty()) { // has required fields but JSON element is null
+          throw new IllegalArgumentException(String.format("The required field(s) %s in NewPetCategoryInlineAllofAllOfCategoryTag is not found in the empty JSON string", NewPetCategoryInlineAllofAllOfCategoryTag.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()));
+      }
+  }
+
+  public static class CustomTypeAdapterFactory implements TypeAdapterFactory {
+    @SuppressWarnings("unchecked")
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+       if (!NewPetCategoryInlineAllofAllOfCategoryTag.class.isAssignableFrom(type.getRawType())) {
+         return null; // this class only serializes 'NewPetCategoryInlineAllofAllOfCategoryTag' and its subtypes
+       }
+       final TypeAdapter<JsonElement> elementAdapter = gson.getAdapter(JsonElement.class);
+       final TypeAdapter<NewPetCategoryInlineAllofAllOfCategoryTag> thisAdapter
+                        = gson.getDelegateAdapter(this, TypeToken.get(NewPetCategoryInlineAllofAllOfCategoryTag.class));
+
+       return (TypeAdapter<T>) new TypeAdapter<NewPetCategoryInlineAllofAllOfCategoryTag>() {
+           @Override
+           public void write(JsonWriter out, NewPetCategoryInlineAllofAllOfCategoryTag 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 NewPetCategoryInlineAllofAllOfCategoryTag read(JsonReader in) throws IOException {
+             JsonElement jsonElement = elementAdapter.read(in);
+             validateJsonElement(jsonElement);
+             JsonObject jsonObj = jsonElement.getAsJsonObject();
+             // store additional fields in the deserialized instance
+             NewPetCategoryInlineAllofAllOfCategoryTag 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 NewPetCategoryInlineAllofAllOfCategoryTag given an JSON string
+  *
+  * @param jsonString JSON string
+  * @return An instance of NewPetCategoryInlineAllofAllOfCategoryTag
+  * @throws IOException if the JSON string is invalid with respect to NewPetCategoryInlineAllofAllOfCategoryTag
+  */
+  public static NewPetCategoryInlineAllofAllOfCategoryTag fromJson(String jsonString) throws IOException {
+    return JSON.getGson().fromJson(jsonString, NewPetCategoryInlineAllofAllOfCategoryTag.class);
+  }
+
+ /**
+  * Convert an instance of NewPetCategoryInlineAllofAllOfCategoryTag to an JSON string
+  *
+  * @return JSON string
+  */
+  public String toJson() {
+    return JSON.getGson().toJson(this);
+  }
+}
+

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

@@ -0,0 +1,55 @@
+/*
+ * 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.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for NewPetCategoryInlineAllofAllOfCategoryTag
+ */
+public class NewPetCategoryInlineAllofAllOfCategoryTagTest {
+    private final NewPetCategoryInlineAllofAllOfCategoryTag model = new NewPetCategoryInlineAllofAllOfCategoryTag();
+
+    /**
+     * Model tests for NewPetCategoryInlineAllofAllOfCategoryTag
+     */
+    @Test
+    public void testNewPetCategoryInlineAllofAllOfCategoryTag() {
+        // TODO: test NewPetCategoryInlineAllofAllOfCategoryTag
+    }
+
+    /**
+     * Test the property 'id'
+     */
+    @Test
+    public void idTest() {
+        // TODO: test id
+    }
+
+    /**
+     * Test the property 'name'
+     */
+    @Test
+    public void nameTest() {
+        // TODO: test name
+    }
+
+}

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

@@ -0,0 +1,64 @@
+/*
+ * 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.NewPetCategoryInlineAllofAllOfCategoryTag;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for NewPetCategoryInlineAllof
+ */
+public class NewPetCategoryInlineAllofTest {
+    private final NewPetCategoryInlineAllof model = new NewPetCategoryInlineAllof();
+
+    /**
+     * Model tests for NewPetCategoryInlineAllof
+     */
+    @Test
+    public void testNewPetCategoryInlineAllof() {
+        // TODO: test NewPetCategoryInlineAllof
+    }
+
+    /**
+     * Test the property 'id'
+     */
+    @Test
+    public void idTest() {
+        // TODO: test id
+    }
+
+    /**
+     * Test the property 'name'
+     */
+    @Test
+    public void nameTest() {
+        // TODO: test name
+    }
+
+    /**
+     * Test the property 'categoryTag'
+     */
+    @Test
+    public void categoryTagTest() {
+        // TODO: test categoryTag
+    }
+
+}

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

@@ -0,0 +1,100 @@
+/*
+ * 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 java.util.ArrayList;
+import java.util.List;
+import org.openapitools.client.model.Category;
+import org.openapitools.client.model.NewPetCategoryInlineAllof;
+import org.openapitools.client.model.Tag;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for NewPet
+ */
+public class NewPetTest {
+    private final NewPet model = new NewPet();
+
+    /**
+     * Model tests for NewPet
+     */
+    @Test
+    public void testNewPet() {
+        // TODO: test NewPet
+    }
+
+    /**
+     * Test the property 'id'
+     */
+    @Test
+    public void idTest() {
+        // TODO: test id
+    }
+
+    /**
+     * Test the property 'categoryInlineAllof'
+     */
+    @Test
+    public void categoryInlineAllofTest() {
+        // TODO: test categoryInlineAllof
+    }
+
+    /**
+     * Test the property 'categoryAllOfRef'
+     */
+    @Test
+    public void categoryAllOfRefTest() {
+        // TODO: test categoryAllOfRef
+    }
+
+    /**
+     * Test the property 'name'
+     */
+    @Test
+    public void nameTest() {
+        // TODO: test name
+    }
+
+    /**
+     * Test the property 'photoUrls'
+     */
+    @Test
+    public void photoUrlsTest() {
+        // TODO: test photoUrls
+    }
+
+    /**
+     * Test the property 'tags'
+     */
+    @Test
+    public void tagsTest() {
+        // TODO: test tags
+    }
+
+    /**
+     * Test the property 'status'
+     */
+    @Test
+    public void statusTest() {
+        // TODO: test status
+    }
+
+}