Add ItemStack Recipe API helper methods

Allows using ExactChoice Recipes with easier methods

Redirects some of upstream's APIs to these new methods to avoid
usage of magic values and the deprecated RecipeChoice#getItemStack

paper-api/src/main/java/org/bukkit/inventory/RecipeChoice.java

@@ -157,8 +157,6 @@ public interface RecipeChoice extends Predicate<ItemStack>, Cloneable {
     /**
      * Represents a choice that will be valid only if one of the stacks is
      * exactly matched (aside from stack size).
-     * <br>
-     * <b>Only valid for shaped recipes</b>
      */
     public static class ExactChoice implements RecipeChoice {
 

paper-api/src/main/java/org/bukkit/inventory/ShapedRecipe.java

@@ -180,6 +180,13 @@ public class ShapedRecipe extends CraftingRecipe {
         return this;
     }
 
+    // Paper start
+    @NotNull
+    public ShapedRecipe setIngredient(char key, @NotNull ItemStack item) {
+        return setIngredient(key, new RecipeChoice.ExactChoice(item));
+    }
+    // Paper end
+
     /**
      * Get a copy of the ingredients map.
      *

paper-api/src/main/java/org/bukkit/inventory/ShapelessRecipe.java

@@ -132,6 +132,40 @@ public class ShapelessRecipe extends CraftingRecipe {
         return this;
     }
 
+    // Paper start
+    @NotNull
+    public ShapelessRecipe addIngredient(@NotNull ItemStack item) {
+        return addIngredient(item.getAmount(), item);
+    }
+
+    @NotNull
+    public ShapelessRecipe addIngredient(int count, @NotNull ItemStack item) {
+        Preconditions.checkArgument(ingredients.size() + count <= 9, "Shapeless recipes cannot have more than 9 ingredients");
+        while (count-- > 0) {
+            ingredients.add(new RecipeChoice.ExactChoice(item));
+        }
+        return this;
+    }
+
+    @NotNull
+    public ShapelessRecipe removeIngredient(@NotNull ItemStack item) {
+        return removeIngredient(1, item);
+    }
+
+    @NotNull
+    public ShapelessRecipe removeIngredient(int count, @NotNull ItemStack item) {
+        Iterator<RecipeChoice> iterator = ingredients.iterator();
+        while (count > 0 && iterator.hasNext()) {
+            RecipeChoice choice = iterator.next();
+            if (choice.test(item)) {
+                iterator.remove();
+                count--;
+            }
+        }
+        return this;
+    }
+    // Paper end
+
     /**
      * Removes an ingredient from the list.
      *
@@ -155,7 +189,7 @@ public class ShapelessRecipe extends CraftingRecipe {
      */
     @NotNull
     public ShapelessRecipe removeIngredient(@NotNull Material ingredient) {
-        return removeIngredient(ingredient, 0);
+        return removeIngredient(new ItemStack(ingredient)); // Paper - avoid using deprecated methods (magic values; RecipeChoice#getItemStack)
     }
 
     /**
@@ -182,7 +216,7 @@ public class ShapelessRecipe extends CraftingRecipe {
      */
     @NotNull
     public ShapelessRecipe removeIngredient(int count, @NotNull Material ingredient) {
-        return removeIngredient(count, ingredient, 0);
+        return removeIngredient(count, new ItemStack(ingredient)); // Paper - avoid using deprecated methods (magic values; RecipeChoice#getItemStack)
     }
 
     /**