PaperMC/nms-patches/TileEntityShulkerBox.patch

--- a/net/minecraft/server/TileEntityShulkerBox.java
+++ b/net/minecraft/server/TileEntityShulkerBox.java
@@ -3,6 +3,10 @@
 import java.util.List;
 import java.util.stream.IntStream;
 import javax.annotation.Nullable;
+// CraftBukkit start
+import org.bukkit.craftbukkit.entity.CraftHumanEntity;
+import org.bukkit.entity.HumanEntity;
+// CraftBukkit end
 
 public class TileEntityShulkerBox extends TileEntityLootable implements IWorldInventory, ITickable {
 
@@ -16,6 +20,36 @@
     private EnumColor l;
     private boolean m;
 
+    // CraftBukkit start - add fields and methods
+    public List<HumanEntity> transaction = new java.util.ArrayList<HumanEntity>();
+    private int maxStack = MAX_STACK;
+
+    public List<ItemStack> getContents() {
+        return this.contents;
+    }
+
+    public void onOpen(CraftHumanEntity who) {
+        transaction.add(who);
+    }
+
+    public void onClose(CraftHumanEntity who) {
+        transaction.remove(who);
+    }
+
+    public List<HumanEntity> getViewers() {
+        return transaction;
+    }
+
+    @Override
+    public int getMaxStackSize() {
+        return maxStack;
+    }
+
+    public void setMaxStackSize(int size) {
+        maxStack = size;
+    }
+    // CraftBukkit end
+
     public TileEntityShulkerBox(@Nullable EnumColor enumcolor) {
         super(TileEntityTypes.SHULKER_BOX);
         this.contents = NonNullList.a(27, ItemStack.b);