*/
  public <T extends @Nullable Object> ListenableFuture<T> submitAsync(
      AsyncCallable<T> callable, Executor executor) {
    checkNotNull(callable);
    checkNotNull(executor);
    TaskNonReentrantExecutor taskExecutor = new TaskNonReentrantExecutor(executor, this);
    AsyncCallable<T> task =
        new AsyncCallable<T>() {
          @Override
          public ListenableFuture<T> call() throws Exception {