protected function getUrlFromConfiguration($routeName, $configuration, $item = null)
    {
        foreach ($configuration['route_parameters'] as $key=>$parameter) {
            $configuration['route_parameters'][$key] = $this->getItemParameter($item, $parameter);
        }
        
        $url = $this->router->generate($routeName, $configuration['route_parameters']);
        
        $urlObject = new Url(
                $url,
                (isset($configuration['last_mod']) ? $this->getItemParameter($item, $configuration['last_mod']) : null),
                (isset($configuration['priority']) ? $this->getItemParameter($item, $configuration['priority']) : null),
                (isset($configuration['change_freq']) ? $this->getItemParameter($item, $configuration['change_freq']) : null)
        );
        return $urlObject;
    }