public function ordersUpload(array $orders, $site = null)
    {
        if (!count($orders)) {
            throw new \InvalidArgumentException(
                'Parameter `orders` must contains array of the orders'
            );
        }

        /* @noinspection PhpUndefinedMethodInspection */
        return $this->client->makeRequest(
            '/orders/upload',
            "POST",
            $this->fillSite($site, ['orders' => json_encode($orders)])
        );
    }