code: @Override
      public boolean isNonWorkingDay(final E date) {
          if (date != null && (holidayCalendar.getEarlyBoundary() != null || holidayCalendar.getLateBoundary() != null)) {
              checkBoundary(date);
          }
          return isWeekend(date) || holidayCalendar.isHoliday(date);
      }
docs: is the given date a non working day?