log.Debugf("MergeGateways: merging gateway %q :\n%v", gatewayName, gatewayCfg)
		snames := sets.String{}
		for _, s := range gatewayCfg.Servers {
			if len(s.Name) > 0 {
				if snames.InsertContains(s.Name) {
					log.Warnf("Server name %s is not unique in gateway %s and may create possible issues like stat prefix collision ",
						s.Name, gatewayName)
				}
			}
			if s.Port == nil {

	got := sets.New[string]()
	for wname := range addresses {
		wl := a.Lookup(wname)
		if len(wl) == 0 {
			removed = append(removed, wname)
		} else {
			for _, addr := range wl {
				if !got.InsertContains(addr.ResourceName()) {
					res = append(res, addr)
				}
			}
		}
	}
	return res, sets.New(removed...)
}

func (a *index) ServicesForWaypoint(key model.WaypointKey) []model.ServiceInfo {

	found := sets.New[endpointKey]()
	for _, eps := range e.endpointsByServiceAndSlice[hostname] {
		for _, ep := range eps {
			key := endpointKey{ep.Address, ep.ServicePortName}
			if found.InsertContains(key) {
				// This a duplicate. Update() already handles conflict resolution, so we don't
				// need to pick the "right" one here.
				continue
			}
			endpoints = append(endpoints, ep)
		}
	}

	register func(f erasedEventHandler),
) {
	i.d = append(i.d, d)

	// For any new collections we depend on, start watching them if its the first time we have watched them.
	if !i.collectionDependencies.InsertContains(d.id) {
		i.log.WithLabels("collection", d.collectionName).Debugf("register new dependency")
		syncer.WaitUntilSynced(i.stop)
		register(func(o []Event[any], initialSync bool) {
			i.onSecondaryDependencyEvent(d.id, o)

	}
	return res, nil
}

func removeDuplicates(values []string) []string {
	set := sets.New[string]()
	newValues := make([]string, 0, len(values))
	for _, v := range values {
		if !set.InsertContains(v) {
			newValues = append(newValues, v)
		}
	}
	return newValues

	if tlsDefaults := mesh.TlsDefaults; tlsDefaults != nil {
		for _, cs := range tlsDefaults.EcdhCurves {
			if !security.IsValidECDHCurve(cs) {
				unrecognizedECDHCurves.Insert(cs)
			} else if validECDHCurves.InsertContains(cs) {
				duplicateECDHCurves.Insert(cs)
			}
		}
	}

	if len(unrecognizedECDHCurves) > 0 {
		v = AppendWarningf(v, "detected unrecognized ECDH curves: %v", sets.SortedList(unrecognizedECDHCurves))
	}

	// for any clusters that share the same name the first cluster is kept and the others are discarded.
	have := sets.String{}
	out := make([]*discovery.Resource, 0, len(clusters))
	for _, c := range clusters {
		if !have.InsertContains(c.Name) {
			out = append(out, c)
		} else {
			cb.req.Push.AddMetric(model.DuplicatedClusters, c.Name, cb.proxyID,
				fmt.Sprintf("Duplicate cluster %s found while pushing CDS", c.Name))
		}
	}

	knownFQDN := sets.String{}

	buildVirtualHost := func(hostname string, vhwrapper istio_route.VirtualHostWrapper, svc *model.Service) *route.VirtualHost {
		name := util.DomainName(hostname, vhwrapper.Port)
		if vhosts.InsertContains(name) {
			// This means this virtual host has caused duplicate virtual host name.
			var msg string
			if svc == nil {
				msg = fmt.Sprintf("duplicate domain from virtual service: %s", name)
			} else {