Fix pkill() on latest 1.20.4 builds

This does now cause a damage event that is cancellable. It also changes the damage cause from CUSTOM to KILL, but this is appropriate and in line with other changes, as KILL didn't previously exist.

src/main/java/com/laytonsmith/abstraction/bukkit/entities/BukkitMCLivingEntity.java

@@ -1,5 +1,6 @@
 package com.laytonsmith.abstraction.bukkit.entities;
 
+import com.laytonsmith.PureUtilities.Common.ReflectionUtils;
 import com.laytonsmith.abstraction.MCAttributeModifier;
 import com.laytonsmith.abstraction.MCEntity;
 import com.laytonsmith.abstraction.MCEntityEquipment;
@@ -26,11 +27,14 @@
 import org.bukkit.attribute.AttributeInstance;
 import org.bukkit.attribute.AttributeModifier;
 import org.bukkit.block.Block;
+import org.bukkit.damage.DamageSource;
+import org.bukkit.damage.DamageType;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Mob;
 import org.bukkit.entity.Player;
 import org.bukkit.event.entity.EntityDamageEvent;
+import org.bukkit.event.entity.EntityDamageEvent.DamageCause;
 import org.bukkit.potion.PotionEffect;
 import org.bukkit.potion.PotionEffectType;
 import org.bukkit.util.BlockIterator;
@@ -346,8 +350,16 @@ public void setTarget(MCLivingEntity target, Target t) {
 
 	@Override
 	public void kill() {
-		le.setLastDamageCause(new EntityDamageEvent(le, EntityDamageEvent.DamageCause.CUSTOM, le.getHealth()));
-		le.setHealth(0D);
+		try {
+			le.damage(le.getHealth(), DamageSource.builder(DamageType.GENERIC_KILL).build());
+		} catch (NoClassDefFoundError | NoSuchMethodError ex) {
+			// probably before 1.20.4
+			EntityDamageEvent event = ReflectionUtils.newInstance(EntityDamageEvent.class,
+					new Class[]{Entity.class, DamageCause.class, double.class},
+					new Object[]{le, EntityDamageEvent.DamageCause.CUSTOM, le.getHealth()});
+			le.setLastDamageCause(event);
+			le.setHealth(0);
+		}
 	}
 
 	@Override