[Python] Do not use mutable default argument

[jirikuncar]

Avoid using mutable default arguments in Python.

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project before.
• Run the shell script(s) under ./bin/ (or Windows batch scripts under.\bin\windows) to update Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit, and these must match the expectations made by your contribution. You only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the code or mustache templates for a language ({LANG}) (e.g. php, ruby, python, etc).
• File the PR against the correct branch: master, 4.3.x, 5.0.x. Default: master.
• Copy the technical committee to review the pull request if your PR is targeting a particular programming language.

--
cc @taxpon (2017/07) @frol (2017/07) @mbohlool (2017/07) @cbornet (2017/09) @kenjones-cisco (2017/11) @tomplus (2018/10) @Jyhess (2019/01) @slash-arun (2019/11) @spacether (2019/11)

[jirikuncar]

@spacether thank you for the review. I have cleaned up the configuration template even more based on your suggestions.

[spacether]

@jirikuncar it sounds like there may have been a misunderstanding here. My comments were asking that you preserve the docstring information from the setters as you were deleting the types shown there. I also give a reason why the docstring for both the getter and the setter exists in the getter. In my opinion having the docstring in the getter + setter is helpful for the following reasons. As a dev I want to be able to:

• read a getter docstring to understand what I get
• read a setter docstring to understand what I need to set
• use the help(ClassName) in the python terminal to read getter docstring and read what we need to get/set. In my comments I didn't ask that you delete the setter docstrings.

If you want to delete the setter docstrings I am okay with that as long as the needed information still exists in the getter docstrings.

[spacether]

Please add a type description to this docstring
We are losing the information when we delete it from the setter

[jirikuncar]

@spacether I don't get your comment.

    @property
    def debug(self):
        """The debug status.

        :param value: The debug status, True or False.
        :type: bool
        """

[spacether]

Sorry, my mistake, I missed the remaining bool type here. This is good.

[spacether]

@jirikuncar can you check out the Travis CI error here?
https://travis-ci.org/OpenAPITools/openapi-generator/builds/618563611?utm_source=github_status&utm_medium=notification
It looks like there are python errors in CI testing there.

[jirikuncar]

I might revisit this one in the future by updating docstrings to follow PEP 257 (pydocstyle).

A minimal changed for mutable defaults has been moved to #4665.