static List<byte[]> toBytesList(Reply[] replies) {
    List<byte[]> list = new ArrayList<byte[]>(replies.length);
    for (Reply reply : replies) {
      Object data = reply.data();
      if (data == null) {
        list.add(null);
      } else if (data instanceof byte[]) list.add((byte[]) data);
      else
        throw new IllegalArgumentException(
            "array contains more then just nulls and bytes -> " + data);
    }

    return list;
  }
 public void onSuccess(Reply result) {
   results.add(result.data());
 }