Add test case : arbitraryObjectResponseWithAdditionalProperty

modules/openapi-generator/src/test/java/org/openapitools/codegen/InlineModelResolverTest.java

@@ -602,6 +602,27 @@ public void arbitraryObjectResponseArrayInline() {
         assertNull(arbitaryObject.getProperties());
     }
 
+    @Test
+    public void arbitraryObjectResponseWithAdditionalProperty() {
+        OpenAPI openAPI = new OpenAPIParser().readLocation("src/test/resources/3_0/inline_model_resolver.yaml", null, new ParseOptions()).getOpenAPI();
+        new InlineModelResolver().flatten(openAPI);
+
+        MediaType mediaType = openAPI
+                .getPaths()
+                .get("/arbitrary_object_response_with_additional_property")
+                .getGet()
+                .getResponses()
+                .get("200")
+                .getContent()
+                .get("application/json");
+
+        assertTrue(mediaType.getSchema() instanceof ObjectSchema);
+        assertTrue(mediaType.getSchema().getAdditionalProperties() instanceof ObjectSchema);
+
+        ObjectSchema additionalProperty = (ObjectSchema) mediaType.getSchema().getAdditionalProperties();
+        assertNull(additionalProperty.getProperties());
+    }
+
 /*
     @Test
     public void testArbitraryObjectResponseMapInline() {

modules/openapi-generator/src/test/resources/3_0/inline_model_resolver.yaml

@@ -242,6 +242,18 @@ paths:
                   properties:
                     arbitrary_object_response_array_inline:
                       type: object
+  /arbitrary_object_response_with_additional_property:
+    get:
+      operationId: arbitraryObjectResponseWithAdditionalProperty
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                type: object
+                additionalProperties:
+                  type: object
 components:
   schemas:
     Users: