code: func (s *state) Changed(ns *structs.NodeService, token string) bool {
  	if ns == nil {
  		return true
  	}
  	return ns.Kind != structs.ServiceKindConnectProxy ||
  		s.proxyID != ns.ID ||
  		s.address != ns.Address ||
  		s.port != ns.Port ||
  		!reflect.DeepEqual(s.proxyCfg, ns.Proxy) ||
  		s.token != token
  }
docs: // Changed returns whether or not the passed NodeService has had any of the
  // fields we care about for config state watching changed or a different token.