@Override
    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
        if (msg instanceof ByteBuf && !((ByteBuf) msg).isReadable()) {
            ctx.write(msg, promise);
        } else {
            super.write(ctx, msg, promise);
        }
    }
A Netty handler that logs the I/O traffic of a connection.
core/src/main/java/com/linecorp/armeria/internal/common/TrafficLoggingHandler.java