addSingleDayEvent method
Implementation
void addSingleDayEvent(CalendarEventData<T> event) {
final date = event.date;
if (_singleDayEvents[date] == null) {
_singleDayEvents.addAll({
date: [event],
});
} else {
_singleDayEvents[date]!.addEventInSortedManner(event, _eventSorter);
}
_eventList.add(event);
}