private ZoneId parseExpiryZone(XmlElement expirationTimeEl, FpmlDocument document) { String businessCenter = expirationTimeEl.getChild("businessCenter").getContent(); Optional<ZoneId> optionalZoneId = document.getZoneId(businessCenter); if (!optionalZoneId.isPresent()) { throw new FpmlParseException("Unknown businessCenter" + " attribute value: " + businessCenter); } return optionalZoneId.get(); }