PaperMC/nms-patches/RecipesFurnace.patch

--- a/net/minecraft/server/RecipesFurnace.java
+++ b/net/minecraft/server/RecipesFurnace.java
@@ -10,12 +10,13 @@
     private static final RecipesFurnace a = new RecipesFurnace();
     public Map<ItemStack, ItemStack> recipes = Maps.newHashMap();
     private Map<ItemStack, Float> c = Maps.newHashMap();
+    public Map customRecipes = Maps.newHashMap(); // CraftBukkit - add field
 
     public static RecipesFurnace getInstance() {
         return RecipesFurnace.a;
     }
 
-    private RecipesFurnace() {
+    public RecipesFurnace() { // PAIL: Public
         this.registerRecipe(Blocks.IRON_ORE, new ItemStack(Items.IRON_INGOT), 0.7F);
         this.registerRecipe(Blocks.GOLD_ORE, new ItemStack(Items.GOLD_INGOT), 1.0F);
         this.registerRecipe(Blocks.DIAMOND_ORE, new ItemStack(Items.DIAMOND), 1.0F);
@@ -53,6 +54,12 @@
         this.registerRecipe(Blocks.QUARTZ_ORE, new ItemStack(Items.QUARTZ), 0.2F);
     }
 
+    // CraftBukkit start - add method
+    public void registerRecipe(ItemStack itemstack, ItemStack itemstack1) {
+        this.customRecipes.put(itemstack, itemstack1);
+    }
+    // CraftBukkit end
+
     public void registerRecipe(Block block, ItemStack itemstack, float f) {
         this.a(Item.getItemOf(block), itemstack, f);
     }
@@ -67,13 +74,23 @@
     }
 
     public ItemStack getResult(ItemStack itemstack) {
-        Iterator iterator = this.recipes.entrySet().iterator();
+        // CraftBukkit start - initialize to customRecipes
+        boolean vanilla = false;
+        Iterator iterator = this.customRecipes.entrySet().iterator();
+        // CraftBukkit end
 
         Entry entry;
 
         do {
             if (!iterator.hasNext()) {
-                return null;
+                // CraftBukkit start - fall back to vanilla recipes
+                if (!vanilla && !recipes.isEmpty()) {
+                    iterator = this.recipes.entrySet().iterator();
+                    vanilla = true;
+                } else {
+                    return null;
+                }
+                // CraftBukkit end
             }
 
             entry = (Entry) iterator.next();