handle empty conversion from nms to API

patches/server/1049-Fix-issues-with-Recipe-API.patch

@@ -4,8 +4,21 @@ Date: Sun, 12 May 2024 15:49:36 -0700
 Subject: [PATCH] Fix issues with Recipe API
 
 
+diff --git a/src/main/java/net/minecraft/world/item/crafting/ShapedRecipe.java b/src/main/java/net/minecraft/world/item/crafting/ShapedRecipe.java
+index 482d7b12b80328fba97a01bcfeb974b7ac4bcdb7..fb4c8a2a15e8e3e26454b7da920454e9861336c6 100644
+--- a/src/main/java/net/minecraft/world/item/crafting/ShapedRecipe.java
++++ b/src/main/java/net/minecraft/world/item/crafting/ShapedRecipe.java
+@@ -91,7 +91,7 @@ public class ShapedRecipe extends io.papermc.paper.inventory.recipe.RecipeBookEx
+         char c = 'a';
+         for (Ingredient list : this.pattern.ingredients()) {
+             RecipeChoice choice = CraftRecipe.toBukkit(list);
+-            if (choice != null) {
++            if (choice != RecipeChoice.empty()) { // Paper
+                 recipe.setIngredient(c, choice);
+             }
+ 
 diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftRecipe.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftRecipe.java
-index 6ba29875d78ede4aa7978ff689e588f7fed11528..e1e406c58e429329bb5732a6b8bb5fb2c40db837 100644
+index 6ba29875d78ede4aa7978ff689e588f7fed11528..c76c78bb7757d407102271463e14716a1b012deb 100644
 --- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftRecipe.java
 +++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftRecipe.java
 @@ -29,6 +29,10 @@ public interface CraftRecipe extends Recipe {
@@ -19,6 +32,15 @@ index 6ba29875d78ede4aa7978ff689e588f7fed11528..e1e406c58e429329bb5732a6b8bb5fb2
          } else {
              throw new IllegalArgumentException("Unknown recipe stack instance " + bukkit);
          }
+@@ -45,7 +49,7 @@ public interface CraftRecipe extends Recipe {
+         list.getItems();
+ 
+         if (list.itemStacks.length == 0) {
+-            return null;
++            return RecipeChoice.empty(); // Paper - null breaks API contracts
+         }
+ 
+         if (list.exact) {
 diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftSmithingTransformRecipe.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftSmithingTransformRecipe.java
 index 38690b28b6f67624d68877c1e89ebe30b402b233..3aec771478a6b17353d57e82baac53dd24779e7b 100644
 --- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftSmithingTransformRecipe.java
@@ -43,3 +65,52 @@ index 5d7782b168138383c606a2c52fbdebe1732364ac..61af2fe3534ff67f10310c6c7dec39cf
 +        MinecraftServer.getServer().getRecipeManager().addRecipe(new RecipeHolder<>(CraftNamespacedKey.toMinecraft(this.getKey()), new net.minecraft.world.item.crafting.SmithingTrimRecipe(this.toNMS(this.getTemplate(), false), this.toNMS(this.getBase(), false), this.toNMS(this.getAddition(), false), this.willCopyDataComponents()))); // Paper - Option to prevent data components copy & support empty RecipeChoice
      }
  }
+diff --git a/src/test/java/io/papermc/paper/inventory/recipe/TestRecipeChoice.java b/src/test/java/io/papermc/paper/inventory/recipe/TestRecipeChoice.java
+new file mode 100644
+index 0000000000000000000000000000000000000000..b6816485a2360b936c049b398183658ee18813ec
+--- /dev/null
++++ b/src/test/java/io/papermc/paper/inventory/recipe/TestRecipeChoice.java
+@@ -0,0 +1,24 @@
++package io.papermc.paper.inventory.recipe;
++
++import java.util.Iterator;
++import org.bukkit.Bukkit;
++import org.bukkit.inventory.Recipe;
++import org.bukkit.support.AbstractTestingBase;
++import org.junit.jupiter.api.Test;
++
++import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
++import static org.junit.jupiter.api.Assertions.assertTrue;
++
++class TestRecipeChoice extends AbstractTestingBase {
++
++    @Test
++    void testRecipeChoices() {
++        final Iterator<Recipe> iter = Bukkit.recipeIterator();
++        boolean foundRecipes = false;
++        while (iter.hasNext()) {
++            foundRecipes = true;
++            assertDoesNotThrow(iter::next, "Failed to convert a recipe to Bukkit recipe!");
++        }
++        assertTrue(foundRecipes, "No recipes found!");
++    }
++}
+diff --git a/src/test/java/org/bukkit/support/DummyServer.java b/src/test/java/org/bukkit/support/DummyServer.java
+index d7e24766f383f75ed46123fff1bd0ec926a635b4..a73c16bb7923957113e688fa6fe46cbd68837d3e 100644
+--- a/src/test/java/org/bukkit/support/DummyServer.java
++++ b/src/test/java/org/bukkit/support/DummyServer.java
+@@ -56,6 +56,14 @@ public final class DummyServer {
+             when(instance.getTag(anyString(), any(org.bukkit.NamespacedKey.class), any())).thenAnswer(ignored -> new io.papermc.paper.util.EmptyTag());
+             // paper end - testing additions
+ 
++            // Paper start - add test for recipe conversion
++            when(instance.recipeIterator()).thenAnswer(ignored -> {
++                return com.google.common.collect.Iterators.transform(
++                    AbstractTestingBase.DATA_PACK.getRecipeManager().byType.entries().iterator(),
++                    input -> input.getValue().toBukkitRecipe());
++            });
++            // Paper end - add test for recipe conversion
++
+             Bukkit.setServer(instance);
+         } catch (Throwable t) {
+             throw new Error(t);