private function createFileCache($subClassName, array $cacheConfig, ContainerBuilder $container)
    {
        $cacheDir = $this->getFileCacheDir($cacheConfig, $container);
        Utility::appendParameter('dirs', 'metadata_cache_dir', $cacheDir, $container);

        return new Definition(
            Utility::getLibraryClass($subClassName),
            [$cacheDir]
        );
    }