return errTransitionDateNotMidnight
	}

	*tDate = TransitionDate{trnDate}
	return nil
}

// MarshalXML encodes expiration date if it is non-zero and encodes
// empty string otherwise
func (tDate TransitionDate) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
	if tDate.Time.IsZero() {
		return nil
	}
	return e.EncodeElement(tDate.Format(time.RFC3339), startElement)
}