provider/inmemory.go
func (f *filter) Zones(zones map[string]string) map[string]string {
	result := map[string]string{}
	for zoneID, zoneName := range zones {
		if strings.HasSuffix(zoneName, f.domain) {
			result[zoneID] = zoneName
		}
	}
	return result
}
func (f *filter) Zones(zones map[string]string) map[string]string {
	result := map[string]string{}
	for zoneID, zoneName := range zones {
		if strings.HasSuffix(zoneName, f.domain) {
			result[zoneID] = zoneName
		}
	}
	return result
}
// Zones filters map[zoneID]zoneName for names having f.domain as suffix