protected function newCommonMarkConverter(RootConfig $config)
 {
     $environment = Environment::createCommonMarkEnvironment();
     foreach ($config->getCommonMarkExtensions() as $extension) {
         if (!class_exists($extension)) {
             throw new \RuntimeException(sprintf('CommonMark extension class "%s" does not exists. You must use a FCQN!', $extension));
         }
         $environment->addExtension(new $extension());
     }
     return new \League\CommonMark\Converter(new DocParser($environment), new HtmlRenderer($environment));
 }