Provide cleaner way to damage/kill Player

[TetraTheta]

Is your feature request related to a problem?

Currently, we cannot kill Player with certain Damage Cause.

There is workaround for 'damaging'(not killing) player like this:

player.setLastDamageCause(new EntityDamageEvent(player, EntityDamageEvent.DamageCause.DROWNING, 1000));
player.setHealth(1); // Set health to 0 will print 'Player died', not 'Player drowned'. You cannot kill Player with drowning damage.

But this doesn't applied if you want to 'kill' player because what actually kills the player is player.setHealth(0);. This will just print `Player died', not other death message like 'Player drowned', 'Player suffocated' etc.

Describe the solution you'd like.

Provide method like Player#damage(double damage, DamageCause cause).
This method will damage the player with damage cause provided, or if the damage is higher than Player's current health, it will kill the player with privided damage cause.

I think this would be more fit to Damagable as it has setHealth(double health) method, but I'm not sure that whether it would be useful or not to damage living entities other than Player. If it is, Damagable#damage(double damage, DamageCause cause) would be what I suggest.

Describe alternatives you've considered.

I currently cannot think of alternative way of this. If you have, please let me know about it.

Other

If you think 'Oh, that could be done with this simple code! No need to add complexity to API!', let me know about that code.

I think using Player#damage(damage, cause) would be much cleaner than using multiple event listener, hashset etc.

[molor]

Probably this improvement can also help with fixing Updated-NoCheatPlus/NoCheatPlus#185

[Doc94]

Currently the API not have a easy method for convert the EntityDamageEvent.DamageCause to the NMS DamageSource used in Damagable#damage.. and the DamageCause/DamageSource can use Block or Entity... maybe can work a damage method like setLastDamageCause ex: Damagable#damage(EntityDamageEvent event) for handle all this cases...

about Damagable#setHealth(0) in upstream the logic is if you set this in 0 then run a die with generic DamageSource

[Owen1212055]

I think this PR was supposed to cover this #5191

[Doc94]

I think this PR was supposed to cover this #5191

nice (looks this PR not handle damage by blocks only entity) but the PR looks only need rebase?

[TetraTheta]

I think this is now resolved with upstream's new API thing.