Oftentime we have code like this, e.g. in a protocol:

void send(Message msg) {
    ...
    down_prot.down(new Event(Event.MSG, msg));
}

Most protocols deal mainly with Message types, so adding down(Message msg) and up(Message msg) would simplify the code above to:

void send(Message msg) {
    ...
    down_prot.down(msg);
}

This would also lead to a (massive) reduction of Event class creations.

Downside: this requires a lot of code changes (mainly in protocols)!