use model class for request body with additionalProperties (#16613)

* try out simple fix

* add test case

* generate samples

samples/openapi3/client/petstore/python-aiohttp/docs/FakeApi.md

@@ -23,6 +23,7 @@ Method | HTTP request | Description
 [**test_endpoint_parameters**](FakeApi.md#test_endpoint_parameters) | **POST** /fake | Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트 
 [**test_group_parameters**](FakeApi.md#test_group_parameters) | **DELETE** /fake | Fake endpoint to test group parameters (optional)
 [**test_inline_additional_properties**](FakeApi.md#test_inline_additional_properties) | **POST** /fake/inline-additionalProperties | test inline additionalProperties
+[**test_inline_freeform_additional_properties**](FakeApi.md#test_inline_freeform_additional_properties) | **POST** /fake/inline-freeform-additionalProperties | test inline free-form additionalProperties
 [**test_json_form_data**](FakeApi.md#test_json_form_data) | **GET** /fake/jsonFormData | test json serialization of form data
 [**test_query_parameter_collection_format**](FakeApi.md#test_query_parameter_collection_format) | **PUT** /fake/test-query-parameters | 
 
@@ -1370,6 +1371,71 @@ No authorization required
 
 [[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
 
+# **test_inline_freeform_additional_properties**
+> test_inline_freeform_additional_properties(test_inline_freeform_additional_properties_request)
+
+test inline free-form additionalProperties
+
+
+
+### Example
+
+```python
+import time
+import os
+import petstore_api
+from petstore_api.models.test_inline_freeform_additional_properties_request import TestInlineFreeformAdditionalPropertiesRequest
+from petstore_api.rest import ApiException
+from pprint import pprint
+
+# Defining the host is optional and defaults to http://petstore.swagger.io:80/v2
+# See configuration.py for a list of all supported configuration parameters.
+configuration = petstore_api.Configuration(
+    host = "http://petstore.swagger.io:80/v2"
+)
+
+
+# Enter a context with an instance of the API client
+async with petstore_api.ApiClient(configuration) as api_client:
+    # Create an instance of the API class
+    api_instance = petstore_api.FakeApi(api_client)
+    test_inline_freeform_additional_properties_request = petstore_api.TestInlineFreeformAdditionalPropertiesRequest() # TestInlineFreeformAdditionalPropertiesRequest | request body
+
+    try:
+        # test inline free-form additionalProperties
+        await api_instance.test_inline_freeform_additional_properties(test_inline_freeform_additional_properties_request)
+    except Exception as e:
+        print("Exception when calling FakeApi->test_inline_freeform_additional_properties: %s\n" % e)
+```
+
+
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **test_inline_freeform_additional_properties_request** | [**TestInlineFreeformAdditionalPropertiesRequest**](TestInlineFreeformAdditionalPropertiesRequest.md)| request body | 
+
+### Return type
+
+void (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: application/json
+ - **Accept**: Not defined
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+**200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+
 # **test_json_form_data**
 > test_json_form_data(param, param2)
 

samples/openapi3/client/petstore/python-aiohttp/docs/TestInlineFreeformAdditionalPropertiesRequest.md

@@ -0,0 +1,28 @@
+# TestInlineFreeformAdditionalPropertiesRequest
+
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**some_property** | **str** |  | [optional] 
+
+## Example
+
+```python
+from petstore_api.models.test_inline_freeform_additional_properties_request import TestInlineFreeformAdditionalPropertiesRequest
+
+# TODO update the JSON string below
+json = "{}"
+# create an instance of TestInlineFreeformAdditionalPropertiesRequest from a JSON string
+test_inline_freeform_additional_properties_request_instance = TestInlineFreeformAdditionalPropertiesRequest.from_json(json)
+# print the JSON string representation of the object
+print TestInlineFreeformAdditionalPropertiesRequest.to_json()
+
+# convert the object into a dict
+test_inline_freeform_additional_properties_request_dict = test_inline_freeform_additional_properties_request_instance.to_dict()
+# create an instance of TestInlineFreeformAdditionalPropertiesRequest from a dict
+test_inline_freeform_additional_properties_request_form_dict = test_inline_freeform_additional_properties_request.from_dict(test_inline_freeform_additional_properties_request_dict)
+```
+[[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
+
+