--- a/net/minecraft/server/TileEntityShulkerBox.java
+++ b/net/minecraft/server/TileEntityShulkerBox.java
@@ -3,12 +3,16 @@
 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 {
 
     private static final int[] a = IntStream.range(0, 27).toArray();
     private NonNullList<ItemStack> contents;
-    private int c;
+    public int c; // PAIL private -> public, rename viewerCount
     private TileEntityShulkerBox.AnimationPhase i;
     private float j;
     private float k;
@@ -16,6 +20,37 @@
     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 boolean opened;
+
+    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);
@@ -178,6 +213,7 @@
             }
 
             ++this.c;
+            if (opened) return; // CraftBukkit - only animate if the ShulkerBox hasn't been forced open already by an API call.
             this.world.playBlockAction(this.position, this.getBlock().getBlock(), 1, this.c);
             if (this.c == 1) {
                 this.world.playSound((EntityHuman) null, this.position, SoundEffects.BLOCK_SHULKER_BOX_OPEN, SoundCategory.BLOCKS, 0.5F, this.world.random.nextFloat() * 0.1F + 0.9F);
@@ -190,6 +226,7 @@
     public void closeContainer(EntityHuman entityhuman) {
         if (!entityhuman.isSpectator()) {
             --this.c;
+            if (opened) return; // CraftBukkit - only animate if the ShulkerBox hasn't been forced open already by an API call.
             this.world.playBlockAction(this.position, this.getBlock().getBlock(), 1, this.c);
             if (this.c <= 0) {
                 this.world.playSound((EntityHuman) null, this.position, SoundEffects.BLOCK_SHULKER_BOX_CLOSE, SoundCategory.BLOCKS, 0.5F, this.world.random.nextFloat() * 0.1F + 0.9F);