protected static function _convertManifestVer1_1($vehicles) {
        $manifest = array();
        foreach ($vehicles as $vKey => $vehicle) {
            $entry = $vehicle;
            if (!isset($vehicle['vehicle_class'])) {
                $entry['vehicle_class'] = 'xPDOObjectVehicle';
            }
            if (!isset($vehicle['vehicle_package'])) {
                $entry['vehicle_package'] = 'transport';
            }
            $manifest[] = $entry;
        }
        return $manifest;
    }