@Override
    public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
        infoLog("Connection channel unregistered: {}",
            RemotingUtil.parseRemoteAddress(ctx.channel()));
        super.channelUnregistered(ctx);
    }
@see io.netty.channel.ChannelInboundHandlerAdapter#channelRegistered(io.netty.channel.ChannelHandlerContext)
src/main/java/com/alipay/remoting/ConnectionEventHandler.java