How to use

add

method

in

slimeknights.mantle.util.ItemStackList

 @Override
 protected ItemStackList getDemoTools(ItemStack[][] inputItems) {
  if(inputItems.length == 0) {
   return ItemStackList.create();
  }

  ItemStackList demo = super.getDemoTools(inputItems);

  ItemStackList out = ItemStackList.create();

  for(int i = 0; i < inputItems[0].length; i++) {
   if(inputItems[0][i].getItem() == TinkerTools.sharpeningKit) {
    Material material = TinkerTools.sharpeningKit.getMaterial(inputItems[0][i]);
    IModifier modifier = TinkerRegistry.getModifier("fortify" + material.getIdentifier());
    if(modifier != null) {
     ItemStack stack = demo.get(i % demo.size()).copy();
     modifier.apply(stack);
     out.add(stack);
    }
   }
  }

  return out;
 }
}

/**
 * Create an ItemStackList from the given elements.
 */
public static ItemStackList of(IInventory inventory) {
 ItemStackList itemStackList = withSize(inventory.getSizeInventory());
 for(int i = 0; i < inventory.getSizeInventory(); i++) {
  itemStackList.add(inventory.getStackInSlot(i));
 }
 return itemStackList;
}