Worse case i can do it but not before a week.
Idea is to have each event chains handling a single case.
Versions are 2 cases so should be two chains.
As mentionned in the review it means moving the toggle to the extension probably and drop instanceof from the observer to add typed observes instead of using the base class in the observer.
The thing to take care is to keep our common structure since this code is usable in standalone anf osgi but nothung crazy.
I put a few others notes in the review, one about the doc / backward compat which had been broken - i dont know if ok or not to be honest.
If unclear im happy to fix it all next friday.