apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/service/ConfigsExportService.java/ConfigsExportService/exportClusters
class ConfigsExportService:  private void exportClusters(final Env env, final List<App> exportApps, ZipOutputStream zipOutputStream) {
    exportApps.parallelStream().forEach(exportApp -> {
      try {
        this.exportCluster(env, exportApp, zipOutputStream);
      } catch (Exception e) {
        logger.error("export cluster error. appId = {}", exportApp.getAppId(), e);
      }
    });
  }