public void validateMinMax(FacesContext context) {
        Instant minDate = CalendarUtils.getObjectAsInstant(context, this, getMindate(), PropertyKeys.mindate.name());
        Instant maxDate = CalendarUtils.getObjectAsInstant(context, this, getMaxdate(), PropertyKeys.maxdate.name());
        if (minDate != null && maxDate != null && maxDate.compareTo(minDate) < 0) {
            String id = getClientId(context);
            String component = this.getClass().getSimpleName();
            throw new FacesException(component + " : \"" + id + "\" minimum date must be less than maximum date.");
        }
    }
@see <a href="https://github.com/RobinHerbots/Inputmask/blob/5.x/README_date.md">Inputmask README_date</a>
@param patternTemplate the date pattern
@return the value converted for InputMask plugin
primefaces/src/main/java/org/primefaces/component/api/UICalendar.java