Better handling of allOf in request body (#16991)

* better handling of allOf in request body, add tests

* additional checks

* fix description

samples/client/echo_api/java/feign-gson/api/openapi.yaml

@@ -421,6 +421,24 @@ paths:
       - body
       x-content-type: application/json
       x-accepts: application/json
+  /echo/body/allOf/Pet:
+    post:
+      description: Test body parameter(s)
+      operationId: test/echo/body/allOf/Pet
+      requestBody:
+        $ref: '#/components/requestBodies/AllOfPet'
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Pet'
+          description: Successful operation
+      summary: Test body parameter(s)
+      tags:
+      - body
+      x-content-type: application/json
+      x-accepts: application/json
   /echo/body/Pet/response_string:
     post:
       description: Test empty response body
@@ -541,6 +559,13 @@ components:
           schema:
             $ref: '#/components/schemas/Pet'
       description: Pet object that needs to be added to the store
+    AllOfPet:
+      content:
+        application/json:
+          schema:
+            allOf:
+            - $ref: '#/components/schemas/Pet'
+      description: Pet object that needs to be added to the store
     Tag:
       content:
         application/json:

samples/client/echo_api/java/feign-gson/src/main/java/org/openapitools/client/api/BodyApi.java

@@ -101,6 +101,35 @@ public interface BodyApi extends ApiClient.Api {
 
 
 
+  /**
+   * Test body parameter(s)
+   * Test body parameter(s)
+   * @param pet Pet object that needs to be added to the store (optional)
+   * @return Pet
+   */
+  @RequestLine("POST /echo/body/allOf/Pet")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: application/json",
+  })
+  Pet testEchoBodyAllOfPet(Pet pet);
+
+  /**
+   * Test body parameter(s)
+   * Similar to <code>testEchoBodyAllOfPet</code> but it also returns the http response headers .
+   * Test body parameter(s)
+   * @param pet Pet object that needs to be added to the store (optional)
+   * @return A ApiResponse that wraps the response boyd and the http headers.
+   */
+  @RequestLine("POST /echo/body/allOf/Pet")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: application/json",
+  })
+  ApiResponse<Pet> testEchoBodyAllOfPetWithHttpInfo(Pet pet);
+
+
+
   /**
    * Test free form object
    * Test free form object