private function getServiceItemForMageItem(\Magento\Sales\Api\Data\OrderItemInterface $item, $stockId = null)
    {
        $result = new \Praxigento\Pv\Service\Sale\Data\Item();
        $prodId = $item->getProductId();
        $itemId = $item->getItemId();
        /* qty of the product can be changed in invoice but we use ordered only */
        $qty = $item->getQtyOrdered();
        /* create data item for service */
        $result->setItemId($itemId);
        $result->setProductId($prodId);
        $result->setQuantity($qty);
        $result->setStockId($stockId);
        return $result;
    }