/**
  * Saves an item's data to the database / item meta.
  * Ran after both create and update, so $item->get_id() will be set.
  *
  * @since 2.7.0
  * @param WC_Order_Item $item
  */
 public function save_item_data(&$item)
 {
     wc_update_order_item_meta($item->get_id(), 'discount_amount', $item->get_discount('edit'));
     wc_update_order_item_meta($item->get_id(), 'discount_amount_tax', $item->get_discount_tax('edit'));
 }