A bug with language supporting detection function of component

[howl-anderson]

Rasa version: 2.0.0rc1

Issue:

If a new component has such language supporting settings:

supported_language_list = ["en", "xx"]
not_supported_language_list = None  # which is the default value

it will not work correctly since the can_handle_language function not implemented incorrectly:

        language_list = cls.supported_language_list or []
        not_supported_language_list = cls.not_supported_language_list or []

        return language in language_list or language not in not_supported_language_list

since not_supported_language_list will be [] in our example, so language not in not_supported_language_list will always be true no matter what's the value of language. Finally when cls.not_supported_language_list is None then all language will be supported which is not we wanted.

I will submit a PR to fix it.

[sara-tagger]

Thanks for the issue, @erohmensing will get back to you about it soon!

You may find help in the docs and the forum, too 🤗

[erohmensing]

Thanks for the initiative toward fixing this!

[howl-anderson]

Since #6803 already merged, it fixed the issue, so I will close it now.