public void subscribeToMemberEvents(ActorRef actorRef){
Preconditions.checkNotNull(actorRef, "actorRef should not be null");
cluster.subscribe(actorRef, ClusterEvent.initialStateAsEvents(),
ClusterEvent.MemberEvent.class,
public void subscribeToMemberEvents(ActorRef actorRef){
Preconditions.checkNotNull(actorRef, "actorRef should not be null");
cluster.subscribe(actorRef, ClusterEvent.initialStateAsEvents(),
ClusterEvent.MemberEvent.class,