SPIGOT-4579: Shulker boxes not dropping in creative

nms-patches/PlayerInteractManager.patch

@@ -202,7 +202,7 @@
  
 +            // CraftBukkit start - Special case skulls, their item data comes from a tile entity (Also check if block should drop items)
 +            // And shulker boxes too for duplication on BlockPlaceEvent cancel reasons (Also check if block should drop items)
-+            if ((iblockdata.getBlock() instanceof BlockSkullAbstract || iblockdata.getBlock() instanceof BlockShulkerBox) && !this.isCreative() && event.isDropItems()) {
++            if (((iblockdata.getBlock() instanceof BlockSkullAbstract && !this.isCreative()) || iblockdata.getBlock() instanceof BlockShulkerBox) && event.isDropItems()) {
 +                org.bukkit.block.BlockState state = bblock.getState();
 +                world.captureDrops = new ArrayList<>();
 +