apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/service/AppService.java/AppService/createEnvNavNode
class AppService:  public EnvClusterInfo createEnvNavNode(Env env, String appId) {
    EnvClusterInfo node = new EnvClusterInfo(env);
    node.setClusters(clusterService.findClusters(env, appId));
    return node;
  }