provider/google.go
func separateChange(zones map[string]*dns.ManagedZone, change *dns.Change) map[string]*dns.Change {
	changes := make(map[string]*dns.Change)
	zoneNameIDMapper := zoneIDName{}
	for _, z := range zones {
		zoneNameIDMapper[z.Name] = z.DnsName
		changes[z.Name] = &dns.Change{
			Additions: []*dns.ResourceRecordSet{},
			Deletions: []*dns.ResourceRecordSet{},
		}
	}
	for _, a := range change.Additions {
		if zoneName, _ := zoneNameIDMapper.FindZone(ensureTrailingDot(a.Name)); zoneName != "" {
			changes[zoneName].Additions = append(changes[zoneName].Additions, a)
		} else {
			log.Warnf("No matching zone for record addition: %s %s %s %d", a.Name, a.Type, a.Rrdatas, a.Ttl)
		}
	}

	for _, d := range change.Deletions {
		if zoneName, _ := zoneNameIDMapper.FindZone(ensureTrailingDot(d.Name)); zoneName != "" {
			changes[zoneName].Deletions = append(changes[zoneName].Deletions, d)
		} else {
			log.Warnf("No matching zone for record deletion: %s %s %s %d", d.Name, d.Type, d.Rrdatas, d.Ttl)
		}
	}

	// separating a change could lead to empty sub changes, remove them here.
	for zone, change := range changes {
		if len(change.Additions) == 0 && len(change.Deletions) == 0 {
			delete(changes, zone)
		}
	}

	return changes
}
func separateChange(zones map[string]*dns.ManagedZone, change *dns.Change) map[string]*dns.Change {
	changes := make(map[string]*dns.Change)
	zoneNameIDMapper := zoneIDName{}
	for _, z := range zones {
		zoneNameIDMapper[z.Name] = z.DnsName
		changes[z.Name] = &dns.Change{
			Additions: []*dns.ResourceRecordSet{},
			Deletions: []*dns.ResourceRecordSet{},
		}
	}
	for _, a := range change.Additions {
		if zoneName, _ := zoneNameIDMapper.FindZone(ensureTrailingDot(a.Name)); zoneName != "" {
			changes[zoneName].Additions = append(changes[zoneName].Additions, a)
		} else {
			log.Warnf("No matching zone for record addition: %s %s %s %d", a.Name, a.Type, a.Rrdatas, a.Ttl)
		}
	}

	for _, d := range change.Deletions {
		if zoneName, _ := zoneNameIDMapper.FindZone(ensureTrailingDot(d.Name)); zoneName != "" {
			changes[zoneName].Deletions = append(changes[zoneName].Deletions, d)
		} else {
			log.Warnf("No matching zone for record deletion: %s %s %s %d", d.Name, d.Type, d.Rrdatas, d.Ttl)
		}
	}

	// separating a change could lead to empty sub changes, remove them here.
	for zone, change := range changes {
		if len(change.Additions) == 0 && len(change.Deletions) == 0 {
			delete(changes, zone)
		}
	}

	return changes
}
// separateChange separates a multi-zone change into a single change per zone.