Revert "delete Keys.APPLICABLE_POTION_EFFECTS"

This reverts commit 5b7dab8.

Author: MrHell228

src/main/java/org/spongepowered/api/data/Keys.java

@@ -399,6 +399,11 @@ public final class Keys {
      */
     public static final Key<Value<Integer>> ANGER_LEVEL = Keys.key(ResourceKey.sponge("anger_level"), Integer.class);
 
+    /**
+     * The set of {@link PotionEffect}s applied on use of an {@link ItemStack}.
+     */
+    public static final Key<WeightedCollectionValue<PotionEffect>> APPLICABLE_POTION_EFFECTS = Keys.weightedKey(ResourceKey.sponge("applicable_potion_effects"), PotionEffect.class);
+
     /**
      * The enchantments applied to an {@link ItemStack}.
      *