code: private static void validateSeedBrokers(String[] seedBrokers, Exception exception) {
  		if (!(exception instanceof ClosedChannelException)) {
  			return;
  		}
  		int unknownHosts = 0;
  		for (String broker : seedBrokers) {
  			URL brokerUrl = NetUtils.getCorrectHostnamePort(broker.trim());
  			try {
  				InetAddress.getByName(brokerUrl.getHost());
  			} catch (UnknownHostException e) {
  				unknownHosts++;
  			}
  		}
  		// throw meaningful exception if all the provided hosts are invalid
  		if (unknownHosts == seedBrokers.length) {
  			throw new IllegalArgumentException("All the servers provided in: '"
  				+ ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG + "' config are invalid. (unknown hosts)");
  		}
  	}
docs: Validate that at least one seed broker is valid in case of a
  ClosedChannelException.
  
  @param seedBrokers
  array containing the seed brokers e.g. ["host1:port1",
  "host2:port2"]
  @param exception
  instance