That should be all that is needed, there were some known bugs in Websockets in the Alpha1 release, however I don't think any of them would affect this endpoint.
There is not special config that is needed to enable endpoints, as long as you are using the Undertow subsystem and not JBoss Web. Are you sure websocket.org test page can resolve your endpoint?
Thanks. Not sure quite what resolving an endpoint is? I can see in the Chrome dev tools that there's a connection with status 101 switching protocols and then it sends the default text they use. Little else though.