code: public synchronized void onServerUnavailable(final String id) {
          logger.debug("[onServerUnavailable] id = {}", id);
  
          Server server = getServerById(id);
  
          if (server != null) {
              server.setAvailable(false);
              refreshServers();
          }
      }
docs: Removes a server from the list of available servers.
  @param id Neo4j cluster id