code: @Nonnull
    public CalendarIntervalScheduleBuilder withIntervalInDays (final int intervalInDays)
    {
      _validateInterval (intervalInDays);
      m_nInterval = intervalInDays;
      m_eIntervalUnit = EIntervalUnit.DAY;
      return this;
    }
docs: Specify an interval in the IntervalUnit.DAY that the produced Trigger will
  repeat at.
  
  @param intervalInDays
  the number of days at which the trigger should repeat.
  @return the updated CalendarIntervalScheduleBuilder
  @see ICalendarIntervalTrigger#getRepeatInterval()
  @see ICalendarIntervalTrigger#getRepeatIntervalUnit()