def systemShutdown(system: ActorSystem): Unit def actorStarted(actorRef: ActorRef): Unit def actorStopped(actorRef: ActorRef): Unit def actorTold(actorRef: ActorRef, message: Any, sender: ActorRef): AnyRef def actorReceived(actorRef: ActorRef, message: Any, sender: ActorRef, context: AnyRef): Unit def actorCompleted(actorRef: ActorRef, message: Any, sender: ActorRef, context: AnyRef): Unit // … }