initializeCronTimeZones function
void
initializeCronTimeZones()
Ensures a time zones database is loaded, needed by CronExpression with
a time zone other than UTC: the full one if none is loaded yet. A
database already loaded (e.g. by the application) is kept.
Implementation
void initializeCronTimeZones() {
if (tz.timeZoneDatabase.locations.isEmpty) _loadFullDatabase();
}