PaperMC/nms-patches/ContainerHorse.patch

--- a/net/minecraft/server/ContainerHorse.java
+++ b/net/minecraft/server/ContainerHorse.java
@@ -1,11 +1,31 @@
 package net.minecraft.server;
 
+// CraftBukkit start
+import org.bukkit.craftbukkit.inventory.CraftInventoryView;
+import org.bukkit.inventory.InventoryView;
+// CraftBukkit end
+
 public class ContainerHorse extends Container {
 
     private final IInventory a;
     private final EntityHorseAbstract f;
 
+    // CraftBukkit start
+    org.bukkit.craftbukkit.inventory.CraftInventoryView bukkitEntity;
+    PlayerInventory player;
+
+    @Override
+    public InventoryView getBukkitView() {
+        if (bukkitEntity != null) {
+            return bukkitEntity;
+        }
+
+        return bukkitEntity = new CraftInventoryView(player.player.getBukkitEntity(), a.getOwner().getInventory(), this);
+    }
+
     public ContainerHorse(IInventory iinventory, IInventory iinventory1, final EntityHorseAbstract entityhorseabstract, EntityHuman entityhuman) {
+        player = (PlayerInventory) iinventory;
+        // CraftBukkit end
         this.a = iinventory1;
         this.f = entityhorseabstract;
         boolean flag = true;