apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/service/AppNamespaceService.java/AppNamespaceService/createDefaultAppNamespace
class AppNamespaceService:  @Transactional
  public void createDefaultAppNamespace(String appId) {
    if (!isAppNamespaceNameUnique(appId, ConfigConsts.NAMESPACE_APPLICATION)) {
      throw new BadRequestException(String.format("App already has application namespace. AppId = %s", appId));
    }

    AppNamespace appNs = new AppNamespace();
    appNs.setAppId(appId);
    appNs.setName(ConfigConsts.NAMESPACE_APPLICATION);
    appNs.setComment("default app namespace");
    appNs.setFormat(ConfigFileFormat.Properties.getValue());
    String userId = userInfoHolder.getUser().getUserId();
    appNs.setDataChangeCreatedBy(userId);
    appNs.setDataChangeLastModifiedBy(userId);

    appNamespaceRepository.save(appNs);
  }