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