PaperMC/nms-patches/ContainerHorse.patch

--- a/net/minecraft/server/ContainerHorse.java
+++ b/net/minecraft/server/ContainerHorse.java
@@ -1,12 +1,32 @@
 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 c;
     private final EntityHorseAbstract d;
 
+    // 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(), c.getOwner().getInventory(), this);
+    }
+
     public ContainerHorse(int i, PlayerInventory playerinventory, IInventory iinventory, final EntityHorseAbstract entityhorseabstract) {
         super((Containers) null, i);
+        player = playerinventory;
+        // CraftBukkit end
         this.c = iinventory;
         this.d = entityhorseabstract;
         boolean flag = true;