* fix circular import issue in python flask
This is very similar change to 3678eaff87dd95348470c
All it intends to do is fix the problem of cirular imports (which was
already fixed for python) in the python flask server.
* removal of type hints in quotes
* fix python flask NPE with oas3
* update perl default value, fix example value
* update android sample, fix example value
* restore x-swagger-router-controller for nodejs server generator
* update default value for bash client, fix example value, invalid tag
* update default value for objc
* update objc pestore core data