};

    results.add(serializer.submit(Callables.returning(null), manualExecutor));
    Future<?>[] thingToCancel = new Future<?>[1];
    results.add(
        serializer.submit(
            new Callable<@Nullable Void>() {
              @Override
              public @Nullable Void call() {
                thingToCancel[0].cancel(false);
                return null;
              }
            },