Proper way to start ActorSystem with AKKA Java API

Question

I'm using the Java API for Akka 2.0, and have a sinking feeling that I'm not using the ActorSystem correctly to start and/or/xor stop TypedActors. When the application shuts down, the java process doesn't terminate. Upon debugging, I see that the default dispatcher still has multiple running threads, and the scheduler is still running. Is there anything obvious I'm doing wrong in the example below?

Config akkaConf = ConfigFactory.load();
ActorSystem actorSystem = ActorSystem.create("myApp", akkaConf);

TypedProps<Actor1Impl> actor1TypedProps = new TypedProps<Actor1Impl>(Actor1Interface.class, new Creator<Actor1Impl>(
    public Actor1Impl create() {
        return new Actor1Impl(nonDefault, constructor, scalaIsSo, muchMoreElegant);
    }
);
Actor1Interface a1 = TypedActor.get(actorSystem).typedActorOf(actor1TypedProps, "anA1Actor");

Unbeknownst to the readers (and for the sake of brevity), the Actor1Impl class implements TypedActor.PreStart and .PostStop. In PreStart, it schedules a Runnable task to execute periodically. I thought that could have been keeping the Scheduler active, but I've also saved off the returned Cancellable, which I believe I should cancel in a PostStop block. Which did not help terminate the Scheduler thread. Anyway, back to the story...

There are also a number of other actor types, each with a nonStandard constructor. Some of these register periodic Runnables with the scheduler, as did Actor1Impl above. And to compound the fun, some even require other Actors as constructor arguments, in order for the actors to register for callbacks, like so:

public Actor2Impl(Actor1Interface a1) {
    a1.registerCallback(TypedActor.<Actor2Interface>self());
}

After it is determined that the app has outlived its usefulness, the following is performed:

TypedActor.get(actorSystem).stop(a1);
TypedActor.get(actorSystem).stop(a2);
...
TypedActor.get(actorSystem).stop(aN);
actorSystem.shutdown();

Is there anything I'm doing that is blatantly wrong which would keep the java process from terminating? Specifically, anything which would cause the scheduler and default dispatcher from shutting down?