protected function registerHandler($type)
 {
     $this->handlerRegistry->registerHandler(GraphNavigator::DIRECTION_SERIALIZATION, $type, $this->getFormat(), array($this->handler, 'serializeEnumTo' . ucfirst($this->getFormat())));
 }
 public function registerHandler($direction, $typeName, $format, $handler)
 {
     parent::registerHandler($direction, $typeName, $format, $handler);
     unset($this->initializedHandlers[$direction][$typeName][$format]);
 }