get _calendarTimestamp() {
      if (this.value && this.dateValueUTC && this._checkValueValidity(this.value)) {
        const millisecondsUTC = this.dateValueUTC.getTime();
        return (0, _getRoundedTimestamp.default)(millisecondsUTC);
      }
      return (0, _getTodayUTCTimestamp.default)(this._primaryCalendarType);
    }
Used to provide a timestamp to the Calendar (to focus it to a relevant date when open) based on the component's state
Override in derivatives to provide the calendar a timestamp based on their properties
By default focus the calendar on the selected date if set, or the current day otherwise
@protected
@returns { number } the calendar timestamp