I found this a little hard to grok. The meat of this seems to be that basically this assumes it only sees events from one application. What about something like:
```
This listener expects to hear events from a single application only. If events from multiple
applications are seen, the behavior is unspecified.
```

Then even if this implementation evolves to actually track stuff using the other events, you've already made a general carve-out in the javadoc with the high level assumption.