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/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