public function preApproval(
        $longAccessToken,
        HpsOrderData $orderData = null
    ) {
        $payload = array(
            'LongAccessToken' => $longAccessToken,
            'SubMsgType' => 'cmpi_preapproval',
            'TransactionType' => 'WT',
        );
        return $this->submitTransaction($payload, 'cmpi_baseserver_api');
    }