PaymentOptionSub does not need to be numeric anymore.

Author: Andy Pieters

src/Api/Transaction/Start.php

@@ -306,9 +306,6 @@ public function setPaymentOptionId($paymentOptionId)
 
     public function setPaymentOptionSubId($paymentOptionSubId)
     {
-        if (!is_numeric($paymentOptionSubId)) {
-            throw new Error('PaymentOptionSubId is niet numeriek', 1);
-        }
         $this->_paymentOptionSubId = $paymentOptionSubId;
     }