Django Oauth2 Toolkit custom mixin

Question

I have a particular situation where we're using Django's OAuth2 toolkit. I need to answer a request with a wrong token with a 401 (with a json) instead of a 403 forbidden.

Following this commit I managed to come with this change to:

oauth2_provider/views/mixins.py

class ProtectedResourceMixin(OAuthLibMixin):

        def dispatch(self, request, *args, **kwargs):

            if request.method.upper() == "OPTIONS":
                return super().dispatch(request, *args, **kwargs)

            valid, r = self.verify_request(request)
            if valid:
                request.resource_owner = r.user
                return super().dispatch(request, *args, **kwargs)
            else:

                request.oauth2_error = getattr(r, "oauth2_error", {})
                print(str(self.request.oauth2_error['error']))

                data= {
                            "errors": [
                                    {
                                      "message": str(self.request.oauth2_error['error'])
                                    }
                                ],
                }
                return HttpResponse(json.dumps(data,ensure_ascii=False),content_type="application/json; charset=utf-8",status= 401)
                #return HttpResponseForbidden()

My problem is that even though this solution works it is on the actual file of the library. I would like to implement this without modifying the library.

For my understanding I should be able to create my own custom mixin but I wasn't able to find an example of that sort of implementation, yet.

I'm not using Django rest framework.