We have an event listener that listens to differential & maniphest edits and posts notifications to a HipChat room.
Recently, I updated phabricator and that event listener stopped working. After some digging, I found D8454, where TYPE_DIFFERENTIAL_WILLWRITEREVISION and TYPE_DIFFERENTIAL_DIDWRITEREVISION are removed. It also seems that TYPE_DIFFERENTIAL_WILLSENDMAIL was also removed elsewhere.
Re-introducing these event types would save me a little time, but I think we can probably utilize Herald to do what we need to do (or, even better, T1271).
Anyway, these event types are still present in `PhabricatorEventType.php` as well as https://secure.phabricator.com/book/phabricator/article/events/ - they should probably be removed since they are no longer dispatched.