@Override
          public void operationComplete(ChannelFuture future) throws Exception {
            if (future.isSuccess()) {
              initialize(conf, future.channel(), dnInfo, storageType, writeBlockProtoBuilder,
                timeoutMs, client, locatedBlock.getBlockToken(), promise);
            } else {
              promise.tryFailure(future.cause());
            }
          }
Helper class for implementing {@link FanOutOneBlockAsyncDFSOutput}.
hbase-asyncfs/src/main/java/org/apache/hadoop/hbase/io/asyncfs/FanOutOneBlockAsyncDFSOutputHelper.java