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