PaperMC/paper-server/nms-patches/net/minecraft/world/entity/vehicle/ChestBoat.patch

--- a/net/minecraft/world/entity/vehicle/ChestBoat.java
+++ b/net/minecraft/world/entity/vehicle/ChestBoat.java
@@ -23,6 +23,13 @@
 import net.minecraft.world.item.Items;
 import net.minecraft.world.level.World;
 import net.minecraft.world.level.gameevent.GameEvent;
+// CraftBukkit start
+import java.util.List;
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.entity.CraftHumanEntity;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.inventory.InventoryHolder;
+// CraftBukkit end
 
 public class ChestBoat extends EntityBoat implements HasCustomInventoryScreen, ContainerEntity {
 
@@ -215,4 +222,51 @@
     public void clearItemStacks() {
         this.itemStacks = NonNullList.withSize(this.getContainerSize(), ItemStack.EMPTY);
     }
+
+    // CraftBukkit start
+    public List<HumanEntity> transaction = new java.util.ArrayList<HumanEntity>();
+    private int maxStack = MAX_STACK;
+
+    @Override
+    public List<ItemStack> getContents() {
+        return this.itemStacks;
+    }
+
+    @Override
+    public void onOpen(CraftHumanEntity who) {
+        transaction.add(who);
+    }
+
+    @Override
+    public void onClose(CraftHumanEntity who) {
+        transaction.remove(who);
+    }
+
+    @Override
+    public List<HumanEntity> getViewers() {
+        return transaction;
+    }
+
+    @Override
+    public InventoryHolder getOwner() {
+        org.bukkit.entity.Entity entity = getBukkitEntity();
+        if (entity instanceof InventoryHolder) return (InventoryHolder) entity;
+        return null;
+    }
+
+    @Override
+    public int getMaxStackSize() {
+        return maxStack;
+    }
+
+    @Override
+    public void setMaxStackSize(int size) {
+        maxStack = size;
+    }
+
+    @Override
+    public Location getLocation() {
+        return getBukkitEntity().getLocation();
+    }
+    // CraftBukkit end
 }