code: @Test public void cleanupTest() throws ExecutionException, InterruptedException {
    OrbitStage stage=createStage();
    OrbitStage client=createClient();
    ISomeActor actor1=client.getReference(ISomeActor.class,"1000");
    final Set<UUID> set=new HashSet<>();
    for (int i=0; i < 25; i++) {
      set.add(actor1.getUniqueActivationId().get());
    }
    assertEquals(1,set.size());
    stage.cleanup(true);
    set.add(actor1.getUniqueActivationId().get());
    assertEquals(1,set.size());
    clock.incrementTimeMillis(TimeUnit.MINUTES.toMillis(20));
    stage.cleanup(true);
    set.add(actor1.getUniqueActivationId().get());
    assertEquals(2,set.size());
  }
  