code: public <T> AsyncFutureCallback<T> removeFuture(AsyncFutureCallback<T> asyncFutureCallback) {
  
          this.removeFutureQueue.offer(asyncFutureCallback);
          return asyncFutureCallback;
      }
docs: Remove a callback from the list of callbacks that we are managing.
  
  @param asyncFutureCallback asyncFutureCallback
  @param <T>                 T
  @return the callback that we removed.