Example of Akka EventBus for Java

I think you're just one line short:

final ActorSystem actorSystem = ActorSystem.create("ServerEvents");
final ActorRef actor = actorSystem.actorOf(new Props(SeverEventHandler.class));
actorSystem.eventStream().subscribe(actor,ServerMessage.class);

actorSystem.eventStream().publish(new ServerMessage()); <<== add this

While ServerEventHandler should be something like

public class ServerEventHandler extends UntypedActor {
  @Override
  public void onReceive(final Object message) {
    System.out.println("Got event in thread: " + Thread.currentThread().getName());
    System.out.println("Event: " + message);
  }
}