protected function removePriceInfoFromChildren(array $children)
    {
        foreach ($children as &$child) {
            $child[Tag::UnitPrice] = 0;
            $child[Meta::UnitPriceInc] = 0;
            unset($child[Meta::LineAmount]);
            unset($child[Meta::LineAmountInc]);
            unset($child[Meta::LineDiscountAmountInc]);
        }
        return $children;
    }