Paper/nms-patches/EntityMinecartContainer.patch

--- a/net/minecraft/server/EntityMinecartContainer.java
+++ b/net/minecraft/server/EntityMinecartContainer.java
@@ -1,14 +1,51 @@
 package net.minecraft.server;
 
 import java.util.Random;
+// CraftBukkit start
+import java.util.List;
+import org.bukkit.craftbukkit.entity.CraftHumanEntity;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.inventory.InventoryHolder;
+// CraftBukkit end
 
 public abstract class EntityMinecartContainer extends EntityMinecartAbstract implements ITileInventory, ILootable {
 
-    private ItemStack[] items = new ItemStack[36];
+    private ItemStack[] items = new ItemStack[27]; // CraftBukkit - 36 -> 27
     private boolean b = true;
     private MinecraftKey c;
     private long d;
 
+    // CraftBukkit start
+    public List<HumanEntity> transaction = new java.util.ArrayList<HumanEntity>();
+    private int maxStack = MAX_STACK;
+
+    public ItemStack[] getContents() {
+        return this.items;
+    }
+
+    public void onOpen(CraftHumanEntity who) {
+        transaction.add(who);
+    }
+
+    public void onClose(CraftHumanEntity who) {
+        transaction.remove(who);
+    }
+
+    public List<HumanEntity> getViewers() {
+        return transaction;
+    }
+
+    public InventoryHolder getOwner() {
+        org.bukkit.entity.Entity cart = getBukkitEntity();
+        if(cart instanceof InventoryHolder) return (InventoryHolder) cart;
+        return null;
+    }
+
+    public void setMaxStackSize(int size) {
+        maxStack = size;
+    }
+    // CraftBukkit end
+
     public EntityMinecartContainer(World world) {
         super(world);
     }
@@ -71,7 +108,7 @@
     }
 
     public int getMaxStackSize() {
-        return 64;
+        return maxStack; // CraftBukkit
     }
 
     public Entity c(int i) {