func getFilterChains(l *listener.Listener) []*listener.FilterChain {
	res := l.FilterChains
	if l.DefaultFilterChain != nil {
		res = append(res, l.DefaultFilterChain)
	}
	return res
}

// retrieveListenerType classifies a Listener as HTTP|TCP|HTTP+TCP|UNKNOWN
func retrieveListenerType(l *listener.Listener) string {
	nHTTP := 0
	nTCP := 0
	for _, filterChain := range getFilterChains(l) {
		for _, filter := range filterChain.GetFilters() {