PaperMC/nms-patches/RecipeRepair.patch

--- a/net/minecraft/server/RecipeRepair.java
+++ b/net/minecraft/server/RecipeRepair.java
@@ -2,12 +2,15 @@
 
 import com.google.common.collect.Lists;
 import java.util.List;
+import java.util.stream.Stream; // CraftBukkit
 
-public class RecipeRepair extends IRecipeComplex {
+public class RecipeRepair extends ShapelessRecipes { // CraftBukkit - added extends
 
+    // CraftBukkit start - Delegate to new parent class
     public RecipeRepair(MinecraftKey minecraftkey) {
-        super(minecraftkey);
+        super(minecraftkey, "", new ItemStack(Items.LEATHER_HELMET), NonNullList.a(RecipeItemStack.a, RecipeItemStack.a(Items.LEATHER_HELMET)));
     }
+    // CraftBukkit end
 
     public boolean a(InventoryCrafting inventorycrafting, World world) {
         List<ItemStack> list = Lists.newArrayList();
@@ -67,6 +70,14 @@
                 ItemStack itemstack3 = new ItemStack(itemstack2.getItem());
 
                 itemstack3.setDamage(i1);
+                // CraftBukkit start - Construct a dummy repair recipe
+                NonNullList<RecipeItemStack> ingredients = NonNullList.a();
+                ingredients.add(new RecipeItemStack(Stream.of(new RecipeItemStack.StackProvider(itemstack2.cloneItemStack()))));
+                ingredients.add(new RecipeItemStack(Stream.of(new RecipeItemStack.StackProvider(itemstack.cloneItemStack()))));
+                ShapelessRecipes recipe = new ShapelessRecipes(new MinecraftKey("repairitem"), "", itemstack3.cloneItemStack(), ingredients);
+                inventorycrafting.setCurrentRecipe(recipe);
+                itemstack3 = org.bukkit.craftbukkit.event.CraftEventFactory.callPreCraftEvent(inventorycrafting, inventorycrafting.resultInventory, itemstack3, inventorycrafting.container.getBukkitView(), true);
+                // CraftBukkit end
                 return itemstack3;
             }
         }