PaperMC/nms-patches/BlockShulkerBox.patch

--- a/net/minecraft/server/BlockShulkerBox.java
+++ b/net/minecraft/server/BlockShulkerBox.java
@@ -81,7 +81,31 @@
         super.a(world, blockposition, iblockdata, entityhuman);
     }
 
-    public void dropNaturally(IBlockData iblockdata, World world, BlockPosition blockposition, float f, int i) {}
+    // CraftBukkit start - override to prevent duplication when dropping
+    @Override
+    public void dropNaturally(IBlockData iblockdata, World world, BlockPosition blockposition, float f, int i) {
+        if (true) {
+            TileEntity tileentity = world.getTileEntity(blockposition);
+
+            if (tileentity instanceof TileEntityShulkerBox) {
+                TileEntityShulkerBox tileentityshulkerbox = (TileEntityShulkerBox) tileentity;
+
+                if (!tileentityshulkerbox.s() && tileentityshulkerbox.G()) {
+                    ItemStack itemstack = new ItemStack(this);
+
+                    itemstack.getOrCreateTag().set("BlockEntityTag", ((TileEntityShulkerBox) tileentity).g(new NBTTagCompound()));
+                    if (tileentityshulkerbox.hasCustomName()) {
+                        itemstack.a(tileentityshulkerbox.getCustomName());
+                        tileentityshulkerbox.setCustomName((IChatBaseComponent) null);
+                    }
+
+                    a(world, blockposition, itemstack);
+                }
+            }
+            world.updateAdjacentComparators(blockposition, iblockdata.getBlock());
+        }
+    }
+    // CraftBukkit end
 
     public void postPlace(World world, BlockPosition blockposition, IBlockData iblockdata, EntityLiving entityliving, ItemStack itemstack) {
         if (itemstack.hasName()) {
@@ -98,7 +122,7 @@
         if (iblockdata.getBlock() != iblockdata1.getBlock()) {
             TileEntity tileentity = world.getTileEntity(blockposition);
 
-            if (tileentity instanceof TileEntityShulkerBox) {
+            if (false && tileentity instanceof TileEntityShulkerBox) { // CraftBukkit - moved up
                 TileEntityShulkerBox tileentityshulkerbox = (TileEntityShulkerBox) tileentity;
 
                 if (!tileentityshulkerbox.s() && tileentityshulkerbox.G()) {
@@ -113,8 +137,8 @@
                     a(world, blockposition, itemstack);
                 }
 
-                world.updateAdjacentComparators(blockposition, iblockdata.getBlock());
             }
+            world.updateAdjacentComparators(blockposition, iblockdata.getBlock()); // CraftBukkit - moved down
 
             super.remove(iblockdata, world, blockposition, iblockdata1, flag);
         }