This is a follow-up to https://issues.redhat.com/browse/WELD-2818.
After some discussion on the spec level, it is now forbidden to have wildcard in Event and Instance (which we already check for anyway), but we should also check for a creative use such as Instance<Event<? extends Foo>>.

Note that the specification only enforces checking this at deployment time, not in runtime via dynamic select. That is what we do now as well and I'd prefer to avoid checking runtime so as not to impose validation for every event select/fire which would, most of the time, have no purpose anyway.