code: /** 
   * Sends a bit more messages trying to uncover concurrency issues.
   */
  @Test public void heavierTest() throws ExecutionException, InterruptedException {
    OrbitStage stage1=createStage();
    OrbitStage stage2=createStage();
    IStatelessThing actor1=stage1.getReference(IStatelessThing.class,"1000");
    IStatelessThing actor2=stage2.getReference(IStatelessThing.class,"1000");
    final Set<UUID> set=new HashSet<>();
    set.clear();
    List<Future<UUID>> futures=new ArrayList<>();
    for (int i=0; i < 50; i++) {
      futures.add(actor1.getUniqueActivationId());
      futures.add(actor2.getUniqueActivationId());
    }
    futures.forEach(f -> {
      try {
        set.add(f.get(10,TimeUnit.SECONDS));
      }
   catch (    Exception e) {
        throw new UncheckedException(e);
      }
    }
  );
    assertTrue(set.size() > 1);
    assertTrue(set.size() <= 100);
  }
  