private void Handle(ClusterActorDiscoveryMessage.MonitorActor m)
        {
            _log.Debug($"MonitorActor: Monitor={Sender.Path} Tag={m.Tag}");

            _monitorItems.Add(new MonitorItem {
                Actor = Sender, Tag = m.Tag
            });
            WatchActor(Sender, 1);

            // Send actor up message to just registered monitor

            foreach (var actor in _actorItems.Where(a => a.Tag == m.Tag))
            {
                Sender.Tell(new ClusterActorDiscoveryMessage.ActorUp(actor.Actor, actor.Tag));
            }

            foreach (var node in _nodeMap.Values)
            {
                foreach (var actor in node.ActorItems.Where(a => a.Tag == m.Tag))
                {
                    Sender.Tell(new ClusterActorDiscoveryMessage.ActorUp(actor.Actor, actor.Tag));
                }
            }
        }