SPIGOT-1622: Add drop chance methods for off hand.

src/main/java/org/bukkit/craftbukkit/inventory/CraftEntityEquipment.java

@@ -113,14 +113,36 @@ public class CraftEntityEquipment implements EntityEquipment {
         return entity;
     }
 
+    @Override
     public float getItemInHandDropChance() {
+        return getItemInMainHandDropChance();
+    }
+
+    @Override
+    public void setItemInHandDropChance(float chance) {
+        setItemInMainHandDropChance(chance);
+    }
+
+    @Override
+    public float getItemInMainHandDropChance() {
        return getDropChance(EnumItemSlot.MAINHAND);
     }
 
-    public void setItemInHandDropChance(float chance) {
+    @Override
+    public void setItemInMainHandDropChance(float chance) {
         setDropChance(EnumItemSlot.MAINHAND, chance);
     }
 
+    @Override
+    public float getItemInOffHandDropChance() {
+        return getDropChance(EnumItemSlot.OFFHAND);
+    }
+
+    @Override
+    public void setItemInOffHandDropChance(float chance) {
+        setDropChance(EnumItemSlot.OFFHAND, chance);
+    }
+
     public float getHelmetDropChance() {
         return getDropChance(EnumItemSlot.HEAD);
     }

src/main/java/org/bukkit/craftbukkit/inventory/CraftInventoryPlayer.java

@@ -191,11 +191,33 @@ public class CraftInventoryPlayer extends CraftInventory implements org.bukkit.i
         return (HumanEntity) inventory.getOwner();
     }
 
+    @Override
     public float getItemInHandDropChance() {
+        return getItemInMainHandDropChance();
+    }
+
+    @Override
+    public void setItemInHandDropChance(float chance) {
+        setItemInMainHandDropChance(chance);
+    }
+
+    @Override
+    public float getItemInMainHandDropChance() {
         return 1;
     }
 
-    public void setItemInHandDropChance(float chance) {
+    @Override
+    public void setItemInMainHandDropChance(float chance) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public float getItemInOffHandDropChance() {
+        return 1;
+    }
+
+    @Override
+    public void setItemInOffHandDropChance(float chance) {
         throw new UnsupportedOperationException();
     }