public static function resolveFileName(string $fileName): string
    {
        $suffix = '.php';
        $pathParts = explode($suffix, str_replace(
            [self::$rewriteToPath, DIRECTORY_SEPARATOR . '_proxies'],
            [self::$rootPath, ''],
            $fileName
        ));
        // throw away namespaced path from actual filename
        return $pathParts[0] . $suffix;
    }