static Status getStatus(PipelineAckProto ack) {
    List<Integer> flagList = ack.getFlagList();
    Integer headerFlag;
    if (flagList.isEmpty()) {
      Status reply = ack.getReply(0);
      headerFlag = PipelineAck.combineHeader(ECN.DISABLED, reply);
    } else {
      headerFlag = flagList.get(0);
    }
    return PipelineAck.getStatusFromHeader(headerFlag);
  }
Helper class for implementing {@link FanOutOneBlockAsyncDFSOutput}.
hbase-asyncfs/src/main/java/org/apache/hadoop/hbase/io/asyncfs/FanOutOneBlockAsyncDFSOutputHelper.java