An event which gets called when a PigZombie updates his anger because of another PigZombie, because he got attacked or anything except the normal drop per tick.

It should extend EntityEvent, be cancelable and serve methods like getOldAnger getNewAnger or something like that and maybe a AngerChangeReason?

Just as a side note: https://hub.spigotmc.org/jira/browse/SPIGOT-4211?filter=-2