product example

        if ($product instanceof LineItem) {
            $this->items->add($product);

            /** @var ItemFacade $product */
            $product = $this->get($product->getId());

            return $product;
        }

        $product = $this->helper->product($product, $quantity, $this->context);

        $this->items->add($product);

        /** @var ItemFacade $product */
        $product = $this->get($product->getId());

        return $product;
    }

    /** * `create()` creates a new product line-item for the product with the given id in the given quantity. * Note that the created line-item will not be added automatically to this collection, use `add()` for that. * * @param string $productId The product id for which a line-item should be created. * @param int $quantity Optionally provide the quantity with which the product line-item should be created, defaults to 1. * * @return ItemFacade The newly created product line-item. */