5074 Fix the WebSocket exception handling strategy

[NilsRenaud]

Linked to this issue : #5074

The ConnectionBase exception handler was not set when webSocket.exceptionHandler(...) is called. This was leading ConnectionBase to consider the exception as uncaught and to print it, ignoring the exception handler set at the WebSocketImplBase level.

Moreover, this WebSocket handler was also called after the call to ConnectionBase#handleException(...).

So I decided to set the ConnectionBase exception handler with the WebSocketImplBase.

The replacement of Http1xConnectionBase conn with Http1xConnectionBase<?> conn was needed otherwise the compiler complains.

[vietj]

Your reasoning seems correct to me, however there are a few things we need to improve in this contribution

1. you should address also the HTTP server case that I think will behave the same (looking at Http1xServerConnection)

2. we should test that the related HttpConnection from where it is originating from is not reported the exception, i.e. any exception handler set before upgrading the HttpConnection to a WebSocket will never be called

3. setting up the WebSocketImplBase#handleException as exception handler of HttpConnection will prevent uncaught exception from being logged, so instead of doing so, we could remove the WebSocketImplBase#exceptionHandler field and instead set the exception handler on WebSocketImplBase#conn when it is called (i.e. exceptionHandler(Handler<Throwable> handler) implementation becomes conn.exceptionHandler(handler). Doing this way we need to reroute internal calls reimplement WebSocketImplBase#handleException to delegate to conn#handleException

[vietj]

Great contrib @NilsRenaud ! can you port to master branch ?

[NilsRenaud]

Thanks @vietj I'll do this