#535: Add EntityCategory API to LivingEntity

By: Parker Hawke <hawkeboyz2@hotmail.com>

paper-api/src/main/java/org/bukkit/entity/EntityCategory.java

@@ -0,0 +1,63 @@
+package org.bukkit.entity;
+
+import org.bukkit.enchantments.Enchantment;
+import org.bukkit.potion.PotionEffectType;
+
+/**
+ * A classification of entities which may behave differently than others or be
+ * affected uniquely by enchantments and potion effects among other things.
+ */
+public enum EntityCategory {
+
+    /**
+     * Any uncategorized entity. No additional effects are applied to these
+     * entities relating to a categorization.
+     */
+    NONE,
+    /**
+     * Undead creatures. These creatures:
+     * <ul>
+     *   <li>Are damaged by potions of healing.
+     *   <li>Are healed by potions of harming.
+     *   <li>Are immune to drowning and poison.
+     *   <li>Are subject to burning in daylight (though not all).
+     *   <li>Sink in water (except {@link Drowned}, {@link Phantom Phantoms}
+     *   and {@link Wither Withers}).
+     *   <li>Take additional damage from {@link Enchantment#DAMAGE_UNDEAD}.
+     *   <li>Are ignored by {@link Wither Withers}.
+     * </ul>
+     */
+    UNDEAD,
+    /**
+     * Entities of the arthropod family. These creatures:
+     * <ul>
+     *   <li>Take additional damage and receive {@link PotionEffectType#SLOW}
+     *   from {@link Enchantment#DAMAGE_ARTHROPODS}.
+     *   <li>Are immune to {@link PotionEffectType#POISON} if they are spiders.
+     * </ul>
+     */
+    ARTHROPOD,
+    /**
+     * Entities that participate in raids. These creatures:
+     * <ul>
+     *   <li>Are immune to damage from {@link EvokerFangs}.
+     *   <li>Are ignored by {@link Vindicator vindicators} named "Johnny".
+     *   <li>Are hostile to {@link Villager villagers},
+     *   {@link WanderingTrader wandering traders}, {@link IronGolem iron golems}
+     *   and {@link Player players}.
+     * </ul>
+     */
+    ILLAGER,
+    /**
+     * Entities that reside primarily underwater (excluding {@link Drowned}).
+     * These creatures:
+     * <ul>
+     *   <li>Take additional damage from {@link Enchantment#IMPALING}.
+     *   <li>Are immune to drowning (excluding {@link Dolphin dolphins}).
+     *   <li>Take suffocation damage when out of water for extended periods of
+     *   time (excluding {@link Guardian guardians} and {@link Turtle turtles}).
+     *   <li>Are capable of swimming in water rather than floating or sinking.
+     * </ul>
+     */
+    WATER;
+}

paper-api/src/main/java/org/bukkit/entity/LivingEntity.java

@@ -552,4 +552,15 @@ public interface LivingEntity extends Attributable, Damageable, ProjectileSource
      * @param <T> the type of the passed value
      */
     <T> void setMemory(@NotNull MemoryKey<T> memoryKey, @Nullable T memoryValue);
+
+    /**
+     * Get the category to which this entity belongs.
+     *
+     * Categories may subject this entity to additional effects, benefits or
+     * debuffs.
+     *
+     * @return the entity category
+     */
+    @NotNull
+    public EntityCategory getCategory();
 }