/**
  * Get one value of a property. Returns an empty string if there's no value.
  *
  * @param string $name
  * @return string
  */
 function getProperty($name)
 {
     $op = ObjectProperties::getPropertyByName($this, $name);
     if ($op instanceof ObjectProperty) {
         return $op->getPropertyValue();
     } else {
         return "";
     }
 }