apollo-portal/src/main/java/com/ctrip/framework/apollo/openapi/server/service/ServerItemOpenApiService.java/ServerItemOpenApiService/createOrUpdateItem
class ServerItemOpenApiService:  @Override
  public void createOrUpdateItem(String appId, String env, String clusterName, String namespaceName,
      OpenItemDTO itemDTO) {
    try {
      this.updateItem(appId, env, clusterName, namespaceName, itemDTO);
    } catch (Throwable ex) {
      if (ex instanceof HttpStatusCodeException) {
        // check createIfNotExists
        if (((HttpStatusCodeException) ex).getStatusCode().equals(HttpStatus.NOT_FOUND)) {
          this.createItem(appId, env, clusterName, namespaceName, itemDTO);
          return;
        }
      }
      throw ex;
    }
  }