I've used this library in multiple projects now, it seems that the most useful part is events. I honestly used MutableObject just a few times and its usefulness even then was questionable. If it turns out that the MutableObject functionality is needed, it can be moved to a separate library as not to bloat this one.

Given this, I think the following steps would make most sense (throughout multiple releases):

1. Deprecate MutableObject functionality.
2. Finish up improvements for GameEvent and GameArgumentEvent.
3. Drop MutableObject functionality.
4. Rename the repository to something something *Events, as the focus is only on events.