[BUG][PYTHON-FLASK] Generated flask server missing arguments

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
  -> OpenAPI file provided by this project
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?

Description

Generating a flask pet store server and trying to place order with the default GUI does not work. Placing an order does not seem to require a login (no lock shows in the web interface), even if it did, error 500 wouldn't be appropriate.

openapi-generator version

master 9170e103

OpenAPI declaration file content or url

https://raw.githubusercontent.com/openapitools/openapi-generator/master/modules/openapi-generator/src/test/resources/3_0/petstore.yaml

Generation Details

In this repository's root:

java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate    -i https://raw.githubusercontent.com/openapitools/openapi-generator/master/modules/openapi-generator/src/test/resources/3_0/petstore.yaml    -g python-flask    -o /var/tmp/flask_api_client

Steps to reproduce

• Generate the flask server with the petstore yaml, as described above.
• create, activate, populate a virtual environment (cd /var/tmp/flask_api_client && virtualenv -p python3 venv && . venv/bin/activate && pip install -r requirements.txt)
• start the server (python3 -m openapi_server)
• open the web page URL http://localhost:8080/v2/ui/. The server shows successful requests (200)
• test the endpoint /store/order with the default json structure.

Expected result: do some magic!

Actual result:

{
  "detail": "The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.",
  "status": 500,
  "title": "Internal Server Error",
  "type": "about:blank"
}

Server log:

[2023-09-14 16:50:30,501] ERROR in app: Exception on /v2/store/order [POST]
Traceback (most recent call last):
  File "/var/tmp/flask_api_client/venv/lib/python3.10/site-packages/flask/app.py", line 2077, in wsgi_app
    response = self.full_dispatch_request()
  File "/var/tmp/flask_api_client/venv/lib/python3.10/site-packages/flask/app.py", line 1525, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/var/tmp/flask_api_client/venv/lib/python3.10/site-packages/flask/app.py", line 1523, in full_dispatch_request
    rv = self.dispatch_request()
  File "/var/tmp/flask_api_client/venv/lib/python3.10/site-packages/flask/app.py", line 1509, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
  File "/var/tmp/flask_api_client/venv/lib/python3.10/site-packages/connexion/decorators/decorator.py", line 68, in wrapper
    response = function(request)
  File "/var/tmp/flask_api_client/venv/lib/python3.10/site-packages/connexion/decorators/uri_parsing.py", line 149, in wrapper
    response = function(request)
  File "/var/tmp/flask_api_client/venv/lib/python3.10/site-packages/connexion/decorators/validation.py", line 196, in wrapper
    response = function(request)
  File "/var/tmp/flask_api_client/venv/lib/python3.10/site-packages/connexion/decorators/parameter.py", line 120, in wrapper
    return function(**kwargs)
TypeError: place_order() missing 1 required positional argument: 'order'
127.0.0.1 - - [14/Sep/2023 16:50:30] "POST /v2/store/order HTTP/1.1" 500 -

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/3345

https://github.com/OpenAPITools/openapi-generator/issues/1666

https://github.com/spec-first/connexion/issues/1452

Generate the server from the referenced petstore.yaml, then start it with python3 -m openapi_server and reproduce the POST to /v2/store/order using the default JSON structure. Start from the generated place_order() entry point and the traceback showing its missing order argument. Done means the request no longer returns HTTP 500 and produces the expected do some magic! result.