public function validate()
 {
     $parameterNames = func_get_args()[0];
     foreach ($parameterNames as $parameter) {
         parent::validate($parameter);
     }
 }
 public function validate(array $parameterNames)
 {
     foreach ($parameterNames as $parameter) {
         parent::validate($parameter);
     }
 }
 public function validate()
 {
     parent::validate('card');
     parent::validate('customerReference');
 }