code: protected CompletableFuture<List<String>> remoteWebSocketAddresses(@RpcTargetAddress InetSocketAddress targetAddress, Serializable userid) {
          if (remoteNode == null) return CompletableFuture.completedFuture(null);
          try {
              return remoteNode.getWebSocketAddresses(targetAddress, userid);
          } catch (Exception e) {
              logger.log(Level.WARNING, "remote " + targetAddress + " websocket getOnlineRemoteAddresses error", e);
              return CompletableFuture.completedFuture(null);
          }
      }
docs: 获取目标地址 <br>
  该方法仅供内部调用
  
  @param targetAddress InetSocketAddress
  @param userid        Serializable
  
  @return 客户端地址列表