@Override
public void operationComplete(ChannelFuture channelFuture) throws Exception {
channelFuture.channel().closeFuture().addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
workerGroup.shutdownGracefully();
}
});
if (channelFuture.isSuccess()) {
channel = channelFuture.channel();