code: func (s *StanServer) processCtrlMsg(m *nats.Msg) bool {
  	cm := &spb.CtrlMsg{}
  	// Since we don't use CtrlMsg for connection/subscription close/unsub,
  	// simply return true if CtrlMsg is valid so that this message is ignored.
  	return cm.Unmarshal(m.Data) == nil
  }
docs: // CtrlMsg are no longer used to solve connection and subscription close/unsub
  // ordering issues. However, a (newer) server may still receive those from
  // older servers in the same NATS cluster.
  // Since original behavior was to ignore control messages sent from a server
  // other than itself, and since new server do not send those (in this context
  // at least), this function simply make sure that if it is a properly formed
  // CtrlMsg, we just ignore.