HijriDate
data class HijriDate(val year: Int, val month: Int, val day: Int, val variant: HijriVariant = HijriVariant.UmmAlQura)
A date in the Hijri (Islamic lunar) calendar. month is 1 (Muharram) .. 12 (Dhu al-Hijjah). Construction checks the month and that day is 1..30; toLocalDate also checks the day against the month length of variant.