app/Services/LocalizationService.php
public function calendar(): CalendarInterface
    {
        $non_gregorian_calendars = [
            'ar' => new ArabicCalendar(),
            'fa' => new PersianCalendar(),
            'he' => new JewishCalendar(),
            'yi' => new JewishCalendar(),
        ];

        return $non_gregorian_calendars[$this->locale->languageTag()] ?? new GregorianCalendar();
    }
public function calendar(): CalendarInterface
    {
        $non_gregorian_calendars = [
            'ar' => new ArabicCalendar(),
            'fa' => new PersianCalendar(),
            'he' => new JewishCalendar(),
            'yi' => new JewishCalendar(),
        ];

        return $non_gregorian_calendars[$this->locale->languageTag()] ?? new GregorianCalendar();
    }
public function calendar ( ) : CalendarInterface { $ non_gregorian_calendars = [ 'ar' => new ArabicCalendar ( ) , 'fa' => new PersianCalendar ( ) , 'he' => new JewishCalendar ( ) , 'yi' => new JewishCalendar ( ) , ] ; return $ non_gregorian_calendars [ $ this -> locale -> languageTag ( ) ] ?? new GregorianCalendar ( ) ; }
Which calendar is used in a locale?

@return CalendarInterface
Which calendar is used in a locale?