}
		// do not add hosts, that have already been added
		sniHosts.Insert(h)
	}
	return sets.SortedList(sniHosts)
}

// CheckDuplicates returns all of the hosts provided that are already known
// If there were no duplicates, all hosts are added to the known hosts.
func CheckDuplicates(hosts []string, bind string, knownHosts map[string]string) []string {
	var duplicates []string
	for _, h := range hosts {

						// SNI filter chain matches
						if tlsHostsByPort[listenerPort] == nil {
							tlsHostsByPort[listenerPort] = make(map[string]string)
						}
						if duplicateSniHosts := model.CheckDuplicates(match.SniHosts, server.Bind, tlsHostsByPort[listenerPort]); len(duplicateSniHosts) != 0 {
							log.Warnf(
								"skipping VirtualService %s rule #%v on server port %d of gateway %s, duplicate SNI host names: %v",