* {@link DeadEvent} and reposted.
 *
 * <p>If a subscriber for a supertype of all events (such as Object) is registered, no event will
 * ever be considered dead, and no DeadEvents will be generated. Accordingly, while DeadEvent
 * extends {@link Object}, a subscriber registered to receive any Object will never receive a
 * DeadEvent.
 *
 * <p>This class is safe for concurrent use.
 *