static boolean isWeekend(int dayOfWeek) {
        return dayOfWeek == firstDayOfWeekend || dayOfWeek == lastDayOfWeekend;
    }
Is a day in the week a weekend?

@param dayOfWeek day of week
@return is the day of week a weekend?
stroom-core-client-widget/src/main/java/stroom/widget/datepicker/client/CalendarUtil.java