Cleanup usage of Event classes

This is now all cleaned up.

Not sure about this one:

Careful on early invokations (such as listener methods and processor's execution method), where only object arguments are being used.

Tests seem to be OK.

That is a lot but straightforward. The code is more type safe. I searched for tests and the specific events are well covered.

Thanks for reviewing all this. Yes, it's a lot of extra code that we could now get rid of, fortunately ;-)

Automatically closed - issue fixed for 2 weeks with no activity.