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/native/src/main/java/org/openapitools/client/api/BodyApi.java

@@ -349,6 +349,79 @@ public class BodyApi {
     }
     return localVarRequestBuilder;
   }
+  /**
+   * Test body parameter(s)
+   * Test body parameter(s)
+   * @param pet Pet object that needs to be added to the store (optional)
+   * @return Pet
+   * @throws ApiException if fails to make API call
+   */
+  public Pet testEchoBodyAllOfPet(Pet pet) throws ApiException {
+    ApiResponse<Pet> localVarResponse = testEchoBodyAllOfPetWithHttpInfo(pet);
+    return localVarResponse.getData();
+  }
+
+  /**
+   * Test body parameter(s)
+   * Test body parameter(s)
+   * @param pet Pet object that needs to be added to the store (optional)
+   * @return ApiResponse&lt;Pet&gt;
+   * @throws ApiException if fails to make API call
+   */
+  public ApiResponse<Pet> testEchoBodyAllOfPetWithHttpInfo(Pet pet) throws ApiException {
+    HttpRequest.Builder localVarRequestBuilder = testEchoBodyAllOfPetRequestBuilder(pet);
+    try {
+      HttpResponse<InputStream> localVarResponse = memberVarHttpClient.send(
+          localVarRequestBuilder.build(),
+          HttpResponse.BodyHandlers.ofInputStream());
+      if (memberVarResponseInterceptor != null) {
+        memberVarResponseInterceptor.accept(localVarResponse);
+      }
+      try {
+        if (localVarResponse.statusCode()/ 100 != 2) {
+          throw getApiException("testEchoBodyAllOfPet", localVarResponse);
+        }
+        return new ApiResponse<Pet>(
+          localVarResponse.statusCode(),
+          localVarResponse.headers().map(),
+          localVarResponse.body() == null ? null : memberVarObjectMapper.readValue(localVarResponse.body(), new TypeReference<Pet>() {}) // closes the InputStream
+        );
+      } finally {
+      }
+    } catch (IOException e) {
+      throw new ApiException(e);
+    }
+    catch (InterruptedException e) {
+      Thread.currentThread().interrupt();
+      throw new ApiException(e);
+    }
+  }
+
+  private HttpRequest.Builder testEchoBodyAllOfPetRequestBuilder(Pet pet) throws ApiException {
+
+    HttpRequest.Builder localVarRequestBuilder = HttpRequest.newBuilder();
+
+    String localVarPath = "/echo/body/allOf/Pet";
+
+    localVarRequestBuilder.uri(URI.create(memberVarBaseUri + localVarPath));
+
+    localVarRequestBuilder.header("Content-Type", "application/json");
+    localVarRequestBuilder.header("Accept", "application/json");
+
+    try {
+      byte[] localVarPostBody = memberVarObjectMapper.writeValueAsBytes(pet);
+      localVarRequestBuilder.method("POST", HttpRequest.BodyPublishers.ofByteArray(localVarPostBody));
+    } catch (IOException e) {
+      throw new ApiException(e);
+    }
+    if (memberVarReadTimeout != null) {
+      localVarRequestBuilder.timeout(memberVarReadTimeout);
+    }
+    if (memberVarInterceptor != null) {
+      memberVarInterceptor.accept(localVarRequestBuilder);
+    }
+    return localVarRequestBuilder;
+  }
   /**
    * Test free form object
    * Test free form object

samples/client/echo_api/java/native/src/test/java/org/openapitools/client/CustomTest.java

@@ -60,6 +60,28 @@ public class CustomTest {
         Assert.assertNull(p2);
     }
 
+    /**
+     * Test allOf body parameter(s)
+     * <p>
+     * Test allOf body parameter(s)
+     *
+     * @throws ApiException if the Api call fails
+     */
+    @Test
+    public void testEchoBodyAllOfPet() throws ApiException {
+        Pet queryObject = new Pet().id(12345L).name("Hello World").
+                photoUrls(Arrays.asList(new String[]{"http://a.com", "http://b.com"})).category(new Category().id(987L).name("new category"));
+
+        Pet p = bodyApi.testEchoBodyAllOfPet(queryObject);
+        Assert.assertNotNull(p);
+        Assert.assertEquals("Hello World", p.getName());
+        Assert.assertEquals(Long.valueOf(12345L), p.getId());
+
+        // response is empty body
+        Pet p2 = bodyApi.testEchoBodyPet(null);
+        Assert.assertNull(p2);
+    }
+
     /**
      * Test query parameter(s)
      * <p>