About timed executor

Timed executor is a service that accepts events as pairs of (LocalDateTime, Callable) and executes each event's Callable not earlier than the specified LocalDateTime. The tasks should be executed according to the value of the LocalDateTime or in the order of events' arrival if their LocalDateTimes are equal. Events may arrive in arbitrary order and be enqueued from different threads. Wittingly overdue events are not accepted and no events are being timed out. It is assumed that there will be enough available resources for supporting any possible system backlog.