Prestashop Module Order Export Modification

The module I want to modify exports orders to an external system. The module is currently checking which module that was used to create payment and adds a variable "paytypeidentifier" based on that. I want to add another loop that, if no matching module was found, then checks for stored payment method in Prestashop and assigns a paytypeidentifier based on that.

Example from the current code. The new loop would be added after this.
>
private static function getOrderTransactionInformation($order)
{
$extra = $payTypeIdentifier = $payTypeReference = $payTypeIdentifierPaySystemUser = $payTypeIdentifierPaySystemUser = "";
$payTypeReference = self::getOrderTransactionNumber($order->id, $order->reference);

switch($order->module) {
case 'invoice':
$payTypeIdentifier = 'I';
break;
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