apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/controller/ClusterController.java/ClusterController/loadCluster
class ClusterController:  @GetMapping(value = "apps/{appId}/envs/{env}/clusters/{clusterName:.+}")
  public ClusterDTO loadCluster(@PathVariable("appId") String appId, @PathVariable String env, @PathVariable("clusterName") String clusterName) {

    return clusterService.loadCluster(appId, Env.valueOf(env), clusterName);
  }