code: public void addDate(ICalDate date, boolean floating, TimeZone tz) {
  		if (date != null && date.hasTime() && !floating && tz != null) {
  			dates.add(date);
  		}
  	}
docs: Records the timezoned date-time values that are being written. This is
  used to generate a DAYLIGHT property for vCalendar objects.
  @param floating true if the date is floating, false if not
  @param tz the timezone to format the date in or null for UTC
  @param date the date value