docs: def user_credentials(self):
          """
          Provides the credentials required to authenticate the user for
          login.
          """
          credentials = {}
          login = self.cleaned_data["login"]
          if app_settings.AUTHENTICATION_METHOD == AuthenticationMethod.EMAIL:
              credentials["email"] = login
          elif (
                  app_settings.AUTHENTICATION_METHOD ==
                  AuthenticationMethod.USERNAME):
              credentials["username"] = login
          else:
              if self._is_login_email(login):
                  credentials["email"] = login
              credentials["username"] = login
          credentials["password"] = self.cleaned_data["password"]
          return credentials