Webhook EPaymentInterface helper functions returns ""

[Jeroenhulshof]

For example:

Helper for EPaymentService->PaymentStatusUpdate values

$webhook = new Bluem($config);
$webhook->getTransactionID();
$webhook->getPaymentReference();
$webhook->getDebtorReference();

returns "" for all of the above helper functions.

Helper for EPaymentService->PaymentStatusUpdate->attributes->entranceCode

Also $webhook->getEntranceCode() returns "".