Improve death events

This adds the ability to cancel the death events and to modify the sound
an entity makes when dying. (In cases were no sound should it will be
called with shouldPlaySound set to false allowing unsilencing of silent
entities)

It makes handling of entity deaths a lot nicer as you no longer need
to listen on the damage event and calculate if the entity dies yourself
to cancel the death which has the benefit of also receiving the dropped
items and experience which is otherwise only properly possible by using
internal code.

== AT ==
public net.minecraft.world.entity.LivingEntity getDeathSound()Lnet/minecraft/sounds/SoundEvent;
public net.minecraft.world.entity.LivingEntity getSoundVolume()F

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -2517,7 +2517,14 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
     @Override
     public void sendHealthUpdate() {
         FoodData foodData = this.getHandle().getFoodData();
-        this.sendHealthUpdate(this.getScaledHealth(), foodData.getFoodLevel(), foodData.getSaturationLevel());
+        // Paper start - cancellable death event
+        ClientboundSetHealthPacket packet = new ClientboundSetHealthPacket(this.getScaledHealth(), foodData.getFoodLevel(), foodData.getSaturationLevel());
+        if (this.getHandle().queueHealthUpdatePacket) {
+            this.getHandle().queuedHealthUpdatePacket = packet;
+        } else {
+            this.getHandle().connection.send(packet);
+        }
+        // Paper end
     }
 
     public void injectScaledMaxHealth(Collection<AttributeInstance> collection, boolean force) {

paper-server/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java

@@ -902,8 +902,15 @@ public class CraftEventFactory {
         CraftDamageSource bukkitDamageSource = new CraftDamageSource(damageSource);
         CraftWorld world = (CraftWorld) entity.getWorld();
         EntityDeathEvent event = new EntityDeathEvent(entity, bukkitDamageSource, drops, victim.getExpReward(world.getHandle(), damageSource.getEntity()));
+        populateFields(victim, event); // Paper - make cancellable
         Bukkit.getServer().getPluginManager().callEvent(event);
 
+        // Paper start - make cancellable
+        if (event.isCancelled()) {
+            return event;
+        }
+        playDeathSound(victim, event);
+        // Paper end
         victim.expToDrop = event.getDroppedExp();
 
         for (org.bukkit.inventory.ItemStack stack : event.getDrops()) {
@@ -921,7 +928,14 @@ public class CraftEventFactory {
         PlayerDeathEvent event = new PlayerDeathEvent(entity, bukkitDamageSource, drops, victim.getExpReward(victim.serverLevel(), damageSource.getEntity()), 0, deathMessage);
         event.setKeepInventory(keepInventory);
         event.setKeepLevel(victim.keepLevel); // SPIGOT-2222: pre-set keepLevel
+        populateFields(victim, event); // Paper - make cancellable
         Bukkit.getServer().getPluginManager().callEvent(event);
+        // Paper start - make cancellable
+        if (event.isCancelled()) {
+            return event;
+        }
+        playDeathSound(victim, event);
+        // Paper end
 
         victim.keepLevel = event.getKeepLevel();
         victim.newLevel = event.getNewLevel();
@@ -944,6 +958,31 @@ public class CraftEventFactory {
         return event;
     }
 
+    // Paper start - helper methods for making death event cancellable
+    // Add information to death event
+    private static void populateFields(net.minecraft.world.entity.LivingEntity victim, EntityDeathEvent event) {
+        event.setReviveHealth(event.getEntity().getAttribute(org.bukkit.attribute.Attribute.MAX_HEALTH).getValue());
+        event.setShouldPlayDeathSound(!victim.silentDeath && !victim.isSilent());
+        net.minecraft.sounds.SoundEvent soundEffect = victim.getDeathSound();
+        event.setDeathSound(soundEffect != null ? org.bukkit.craftbukkit.CraftSound.minecraftToBukkit(soundEffect) : null);
+        event.setDeathSoundCategory(org.bukkit.SoundCategory.valueOf(victim.getSoundSource().name()));
+        event.setDeathSoundVolume(victim.getSoundVolume());
+        event.setDeathSoundPitch(victim.getVoicePitch());
+    }
+
+    // Play death sound manually
+    private static void playDeathSound(net.minecraft.world.entity.LivingEntity victim, EntityDeathEvent event) {
+        if (event.shouldPlayDeathSound() && event.getDeathSound() != null && event.getDeathSoundCategory() != null) {
+            net.minecraft.world.entity.player.Player source = victim instanceof net.minecraft.world.entity.player.Player ? (net.minecraft.world.entity.player.Player) victim : null;
+            double x = event.getEntity().getLocation().getX();
+            double y = event.getEntity().getLocation().getY();
+            double z = event.getEntity().getLocation().getZ();
+            net.minecraft.sounds.SoundEvent soundEffect = org.bukkit.craftbukkit.CraftSound.bukkitToMinecraft(event.getDeathSound());
+            net.minecraft.sounds.SoundSource soundCategory = net.minecraft.sounds.SoundSource.valueOf(event.getDeathSoundCategory().name());
+            victim.level().playSound(source, x, y, z, soundEffect, soundCategory, event.getDeathSoundVolume(), event.getDeathSoundPitch());
+        }
+    }
+    // Paper end
     /**
      * Server methods
      */