The webflow is abruptly stopped here with a *WARN* in logs.
We use a ```J2EContext``` : it means that the additionnal HTTP action has been already written directly to the HTTP response, that's why I'm doing a ```response.flushBuffer();``` here.
The webflow is stopped and an HTTP action (redirection, unauthorized, 200 OK) is done according to the protocol and the client...

I'm not totally satisfied here , but it's the best way I found to get out of the webflow...