code: void updateServer(ServerHeartbeat server, UpdateServerHeartbeat update)
    {
      if (server.isSelf()) {
        return;
      }
      
      String externalId = update.getExternalId();
  
      updateExternal(server, externalId);
  
      // XXX: validation
      server.setSeedIndex(update.getSeedIndex());
  
      if (server.onHeartbeatUpdate(update)) {
        if (server.isUp()) {
          onServerStart(server);
        }
        else {
          onServerStop(server);
        }
      }
    }
docs: Update a server with a heartbeat update.
  
  @param server the server to be updated
  @param update the new update information