code: private boolean isWorkingDay(Calendar date) {
  
          return !ArrayUtils.contains(NON_WORKING_DAYS, date.get(Calendar.DAY_OF_WEEK));
      }
docs: Check, if the day for the provided date is a working day (i.e., not Saturday or Sunday).
  @param date the date to check.
  @return <code>true</code> if the provided date represents a working day, <code>false</code> otherwise.