UDate PersianCalendar::defaultCenturyStart() const {
    // lazy-evaluate systemDefaultCenturyStart
    umtx_initOnce(gSystemDefaultCenturyInit, &initializeSystemDefaultCentury);
    return gSystemDefaultCenturyStart;
}
UDate PersianCalendar::defaultCenturyStart() const {
     
    umtx_initOnce(gSystemDefaultCenturyInit, &initializeSystemDefaultCentury);
    return gSystemDefaultCenturyStart;
}