docs: def BuildApprovalUrn(self, approval_id):
      """Builds approval object urn."""
      event = rdf_events.AuditEvent(
          user=self.token.username,
          action="CLIENT_APPROVAL_REQUEST",
          client=self.subject_urn,
          description=self.reason)
      events.Events.PublishEvent("Audit", event, token=self.token)
  
      return self.ApprovalUrnBuilder(self.subject_urn.Path(), self.token.username,
                                     approval_id)