docs: def get_user_details(self, response):
          """ Complete with additional information from original LTI POST data, as available. """
          data = {}
          # None of them is mandatory
          data['id'] = response.get('user_id', None)
          data['username'] = response.get('custom_username', None)
          if not data['username']:
              data['username'] = response.get('ext_user_username', None)
          data['last_name'] = response.get('lis_person_name_family', None)
          data['email'] = response.get(
              'lis_person_contact_email_primary', None)
          data['first_name'] = response.get('lis_person_name_given', None)
          data['fullname'] = response.get('lis_person_name_full', None)
          logger.debug("User details being used: " + str(data))
          return data