code: public static void start() {
          synchronized (lock) {
              if (registry != null) return;
              try {
                  LOG.info("开始启动zk服务注册入口");
                  registry = new ZkServiceRegistry();
                  FastJsonServiceInstanceSerializer<NodeStatus> serializer = new FastJsonServiceInstanceSerializer<>();
                  registry.serviceDiscovery = ServiceDiscoveryBuilder.builder(NodeStatus.class)
                          .client(ZkConnection.client)
                          .basePath(ZkPathManager.getNodeBasePath())
                          .serializer(serializer)
                          .build();
                  registry.serviceDiscovery.start();
                  LOG.info("zk服务注册入口启动完毕");
                  registerService(EnvUtil.getApplication(), LocalNodeManager.singleton.getFullStatus());
              } catch (Exception e) {
                  throw new RuntimeException("启动zkServiceRegistry失败", e);
              }
          }
      }
docs: 启动服务注册，只有启动了服务注册，才可以调用{@link #registerService(String, NodeStatus)}