[python-nextgen] fix empty dict in body parameter (#15336)

* add more tests for python-nextgen

* update samples

* add fix for empty dict body

* update samples

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

@@ -349,6 +349,46 @@ paths:
       - body
       x-content-type: application/json
       x-accepts: text/plain
+  /echo/body/Tag/response_string:
+    post:
+      description: Test empty json (request body)
+      operationId: test/echo/body/Tag/response_string
+      requestBody:
+        $ref: '#/components/requestBodies/Tag'
+      responses:
+        "200":
+          content:
+            text/plain:
+              schema:
+                type: string
+          description: Successful operation
+      summary: Test empty json (request body)
+      tags:
+      - body
+      x-content-type: application/json
+      x-accepts: text/plain
+  /echo/body/FreeFormObject/response_string:
+    post:
+      description: Test free form object
+      operationId: test/echo/body/FreeFormObject/response_string
+      requestBody:
+        content:
+          application/json:
+            schema:
+              type: object
+        description: Free form object
+      responses:
+        "200":
+          content:
+            text/plain:
+              schema:
+                type: string
+          description: Successful operation
+      summary: Test free form object
+      tags:
+      - body
+      x-content-type: application/json
+      x-accepts: text/plain
   /binary/gif:
     post:
       description: Test binary (gif) response body
@@ -373,6 +413,12 @@ components:
           schema:
             $ref: '#/components/schemas/Pet'
       description: Pet object that needs to be added to the store
+    Tag:
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Tag'
+      description: Tag object
   schemas:
     Category:
       example:

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

@@ -6,6 +6,7 @@ import org.openapitools.client.model.ApiResponse;
 
 import java.io.File;
 import org.openapitools.client.model.Pet;
+import org.openapitools.client.model.Tag;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -42,6 +43,35 @@ public interface BodyApi extends ApiClient.Api {
 
 
 
+  /**
+   * Test free form object
+   * Test free form object
+   * @param body Free form object (optional)
+   * @return String
+   */
+  @RequestLine("POST /echo/body/FreeFormObject/response_string")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: text/plain",
+  })
+  String testEchoBodyFreeFormObjectResponseString(Object body);
+
+  /**
+   * Test free form object
+   * Similar to <code>testEchoBodyFreeFormObjectResponseString</code> but it also returns the http response headers .
+   * Test free form object
+   * @param body Free form object (optional)
+   * @return A ApiResponse that wraps the response boyd and the http headers.
+   */
+  @RequestLine("POST /echo/body/FreeFormObject/response_string")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: text/plain",
+  })
+  ApiResponse<String> testEchoBodyFreeFormObjectResponseStringWithHttpInfo(Object body);
+
+
+
   /**
    * Test body parameter(s)
    * Test body parameter(s)
@@ -99,4 +129,33 @@ public interface BodyApi extends ApiClient.Api {
   ApiResponse<String> testEchoBodyPetResponseStringWithHttpInfo(Pet pet);
 
 
+
+  /**
+   * Test empty json (request body)
+   * Test empty json (request body)
+   * @param tag Tag object (optional)
+   * @return String
+   */
+  @RequestLine("POST /echo/body/Tag/response_string")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: text/plain",
+  })
+  String testEchoBodyTagResponseString(Tag tag);
+
+  /**
+   * Test empty json (request body)
+   * Similar to <code>testEchoBodyTagResponseString</code> but it also returns the http response headers .
+   * Test empty json (request body)
+   * @param tag Tag object (optional)
+   * @return A ApiResponse that wraps the response boyd and the http headers.
+   */
+  @RequestLine("POST /echo/body/Tag/response_string")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: text/plain",
+  })
+  ApiResponse<String> testEchoBodyTagResponseStringWithHttpInfo(Tag tag);
+
+
 }