docs: def list_user_participants(self, id, registration_status=None):
          """
          List user participants.
  
          List users that are (or may be) participating in this appointment group.
          Refer to the Users API for the response fields. Returns no results for
          appointment groups with the "Group" participant_type.
          """
          path = {}
          data = {}
          params = {}
  
          # REQUIRED - PATH - id
          """ID"""
          path["id"] = id
  
          # OPTIONAL - registration_status
          """Limits results to the a given participation status, defaults to "all""""
          if registration_status is not None:
              self._validate_enum(registration_status, ["all", "registered", "registered"])
              params["registration_status"] = registration_status
  
          self.logger.debug("GET /api/v1/appointment_groups/{id}/users with query params: {params} and form data: {data}".format(params=params, data=data, **path))
          return self.generic_request("GET", "/api/v1/appointment_groups/{id}/users".format(**path), data=data, params=params, no_data=True)