@Override
    public void operationComplete(ChannelFuture future) {
      if (future.isSuccess()) {
        future.channel().write(request).addListener(writeResultListener);
        if (content != null) {
          future.channel().write(content).addListener(writeResultListener);
        }
        future.channel().flush();
      } else {
        exception = (Exception) future.cause();
        invokeFutureAndCallback("RequestSender::operationComplete");
      }
    }
Sends the {@link #request} and {@link #content} if the channel connects successfully.
ambry-test-utils/src/main/java/com/github/ambry/rest/NettyClient.java