public DateTimeSettings build() {
            if (referenceTime == null) {
                referenceTime = System.currentTimeMillis();
            }
            return new DateTimeSettings(dateTimePattern, timeZone, localZoneId, referenceTime);
        }
@return A copy of this but without the referenceTime.
stroom-query/stroom-query-api/src/main/java/stroom/query/api/DateTimeSettings.java