SPIGOT-6273: Expose ItemFrame ItemDropChance through API

By: md_5 <git@md-5.net>

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

@@ -33,6 +33,31 @@ public interface ItemFrame extends Hanging {
      */
     public void setItem(@Nullable ItemStack item, boolean playSound);
 
+    /**
+     * Gets the chance of the item being dropped upon this frame's destruction.
+     *
+     * <ul>
+     * <li>A drop chance of 0.0F will never drop
+     * <li>A drop chance of 1.0F will always drop
+     * </ul>
+     *
+     * @return chance of the off hand item being dropped
+     */
+    float getItemDropChance();
+
+    /**
+     * Sets the chance of the off hand item being dropped upon this frame's
+     * destruction.
+     *
+     * <ul>
+     * <li>A drop chance of 0.0F will never drop
+     * <li>A drop chance of 1.0F will always drop
+     * </ul>
+     *
+     * @param chance the chance of off hand item being dropped
+     */
+    void setItemDropChance(float chance);
+
     /**
      * Get the rotation of the frame's item
      *