ChannelHandler which consolidates Channel#flush() / ChannelHandlerContext#flush() operations (which also includes Channel#writeAndFlush(Object) and ChannelOutboundInvoker#writeAndFlush(Object).
ChannelHandler
Channel#flush()
ChannelHandlerContext#flush()
Channel#writeAndFlush(Object)
ChannelOutboundInvoker#writeAndFlush(Object)