docs: public final boolean isVisibleDate(LocalDate date) {
          if (date != null) {
              YearMonth extendedStart = getExtendedStartMonth();
              YearMonth extendedEnd = getExtendedEndMonth();
  
              LocalDate startDate = extendedStart.atDay(1);
              LocalDate endDate = extendedEnd.atEndOfMonth();
  
              if ((date.equals(startDate) || date.isAfter(startDate)) && (date.equals(endDate) || date.isBefore(endDate))) {
                  return true;
              }
          }
          return false;
      }