public function getRevManifest(): array {
        if (is_null(self::$_revManifest)) {
            $manifestPath = APPLICATION_PATH . '/../rev-manifest-' . APPLICATION_ENV . '.json';
            self::$_revManifest = file_exists($manifestPath)
                ? json_decode(file_get_contents($manifestPath), true)
                : [];
        }
        return self::$_revManifest;
    }