Motivation:
At the moment the next / prev references are not set to "null" in the DefaultChannelHandlerContext once the ChannelHandler is removed. This is bad as it basically let users still use the ChannelHandlerContext of a ChannelHandler after it is removed and may produce very suprising behaviour.
Modifications:
- Fail if someone tries to use the ChannelHandlerContext once the ChannelHandler was removed (for outbound operations fail the promise, for inbound fire the error through the ChannelPipeline)
- Fix some handlers to ensure we not use the ChannelHandlerContext after the handler was removed
- Adjust DefaultChannelPipeline / DefaultChannelHandlerContext to fixes races with removal / replacement of handlers
Result:
Cleanup behaviour and make it more predictable for pipeline modifications