/**
  * Force that icons are encoded as reference to the L.contao icon registry.
  *
  * @param EncodeValueEvent $event The subscribed event.
  *
  * @return void
  */
 public function encodeIcons(EncodeValueEvent $event)
 {
     $value = $event->getValue();
     if ($value instanceof Icon) {
         // Do not encode the icon, as it is generated in an separate icon file.
         $event->setSuccessful();
         $event->stopPropagation();
     }
 }