Support for additional hearts in Player#damage

src/main/java/net/minestom/server/entity/LivingEntity.java

@@ -226,6 +226,22 @@ public abstract class LivingEntity extends Entity implements EquipmentHandler {
             entityAnimationPacket.entityId = getEntityId();
             entityAnimationPacket.animation = EntityAnimationPacket.Animation.TAKE_DAMAGE;
             sendPacketToViewersAndSelf(entityAnimationPacket);
+
+            // Additional hearts support
+            if (this instanceof Player) {
+                Player player = (Player) this;
+                float additionalHearts = player.getAdditionalHearts();
+                if (additionalHearts > 0) {
+                    if (damage > additionalHearts) {
+                        damage -= additionalHearts;
+                        player.setAdditionalHearts(0);
+                    } else {
+                        player.setAdditionalHearts(additionalHearts - damage);
+                        damage = 0;
+                    }
+                }
+            }
+
             setHealth(getHealth() - damage);
 
             // play damage sound

src/main/java/net/minestom/server/entity/Player.java

@@ -252,6 +252,7 @@ public class Player extends LivingEntity {
 
     @Override
     public boolean damage(DamageType type, float value) {
+        // Compute final heart based on health and additional hearts
         boolean result = super.damage(type, value);
         if (result) {
             lastDamageSource = type;