Add a way to figure out if entity's Damageable#damage was cancelled

[imDaniX]

Is your feature request related to a problem?

I need to react differently if entity with Damageable#damage was damaged successfully or not. Currently, there's no way to figure it out, as damaging can be cancelled with EntityDamageEvent#setCancelled(true) with no feedback.

Describe the solution you'd like.

Make Damageable#damage methods return boolean, with false on a cancelled event.

Describe alternatives you've considered.

Calling EntityDamageEvent myself (which is unsupported, as events constructors are considered internal) and checking if it was cancelled.
I was thinking about checking entity's health before and after, but the final damage might result in 0, which if different from cancellation.

Other

Damageable#heal might need a similar feature, since EntityRegainHealthEvent is cancellable too.

[electronicboy]

can't change the return type without breaking ABI

[imDaniX]

Then I think it's worth creating a new set of methods like callDamage (or, reflecting underneath methods, damageEntity) with the said or similar implementation. Then the original damage methods can be deprecated indefinitely, and their implementation to be changed to just calling the new methods.
There are plenty of plugins that do add custom weapons and stuff, and to properly consider for PvE/PvP protecting plugins like WorldGuard or CombatLogX, there's always a need for some tricky workarounds.

Otherwise, well, I think it should at least be noted in the javadocs that damaging can be cancelled.