switch {
	case !f.And.isEmpty():
		if err := e.EncodeElement(f.And, xml.StartElement{Name: xml.Name{Local: "And"}}); err != nil {
			return err
		}
	case !f.Tag.IsEmpty():
		if err := e.EncodeElement(f.Tag, xml.StartElement{Name: xml.Name{Local: "Tag"}}); err != nil {
			return err
		}
	default:
		// Always print Prefix field when both And & Tag are empty

	if err := e.EncodeToken(start); err != nil {
		return err
	}
	if err := e.EncodeElement(d.String(), xml.StartElement{Name: xml.Name{Local: "Bucket"}}); err != nil {
		return err
	}
	if d.StorageClass != "" {
		if err := e.EncodeElement(d.StorageClass, xml.StartElement{Name: xml.Name{Local: "StorageClass"}}); err != nil {
			return err
		}
	}

// empty string otherwise
func (rDate RetentionDate) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
	if rDate.IsZero() {
		return nil
	}
	return e.EncodeElement(amztime.ISO8601Format(rDate.Time), startElement)
}

// ObjectRetention specified in
// https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutObjectRetention.html
type ObjectRetention struct {

	if o.isDeleteMarker {
		start.Name.Local = "DeleteMarker"
	} else {
		start.Name.Local = "Version"
	}
	type objectVersionWrapper ObjectVersion
	return e.EncodeElement(objectVersionWrapper(o), start)
}

// DeleteMarkerVersion container for delete marker metadata
type DeleteMarkerVersion struct {
	Key          string