apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/NamespaceService.java/NamespaceService/save
class NamespaceService:  @Transactional
  public Namespace save(Namespace entity) {
    if (!isNamespaceUnique(entity.getAppId(), entity.getClusterName(), entity.getNamespaceName())) {
      throw new ServiceException("namespace not unique");
    }
    entity.setId(0);//protection
    Namespace namespace = namespaceRepository.save(entity);

    auditService.audit(Namespace.class.getSimpleName(), namespace.getId(), Audit.OP.INSERT,
                       namespace.getDataChangeCreatedBy());

    return namespace;
  }