/**
  * @param string      $reference
  * @param int         $amount
  * @param string      $bearer
  * @param string      $validityDate
  * @param string|null $subscriberRef
  */
 public function __construct($reference, $amount, $bearer, $validityDate, $subscriberRef = null)
 {
     parent::__construct($reference, $amount, $subscriberRef);
     $this->bearer = $bearer;
     $this->validityDate = $validityDate;
 }
 public function __construct($reference, $amount, $transactionNumber, $callNumber, $subscriberRef = null)
 {
     parent::__construct($reference, $amount, $subscriberRef);
     $this->transactionNumber = $transactionNumber;
     $this->callNumber = $callNumber;
 }