code: public void doAddNodes() {
      if (log.isDebugEnabled()) {
        log.debug("Node discovery running...");
      }
      Set<CassandraHost> foundHosts = discoverNodes();
      if (foundHosts != null && foundHosts.size() > 0) {
        log.info("Found {} new host(s) in Ring", foundHosts.size());
        for (CassandraHost cassandraHost : foundHosts) {
          log.info("Addding found host {} to pool", cassandraHost);
          cassandraHostConfigurator.applyConfig(cassandraHost);
          connectionManager.addCassandraHost(cassandraHost);
        }
      }
      if (log.isDebugEnabled()) {
        log.debug("Node discovery run complete.");
      }
    }
docs: Find any nodes that are not already in the connection manager but are in
  the cassandra ring and add them