apollo-adminservice/src/main/java/com/ctrip/framework/apollo/adminservice/controller/ClusterController.java/ClusterController/find
class ClusterController:  @GetMapping("/apps/{appId}/clusters")
  public List<ClusterDTO> find(@PathVariable("appId") String appId) {
    List<Cluster> clusters = clusterService.findParentClusters(appId);
    return BeanUtils.batchTransform(ClusterDTO.class, clusters);
  }