protected function setupDriver($useBuiltin)
 {
     if ($useBuiltin) {
         $factory = new WeaselDefaultAnnotationDrivenFactory();
         $driver = $factory->getXmlDriverInstance();
     } else {
         $factory = new WeaselDoctrineAnnotationDrivenFactory();
         $driver = $factory->getXmlDriverInstance();
     }
     $this->mapper = $factory->getJsonMapperInstance();
     $this->driver = $driver;
 }