*
 * <p>Registering a DeadEvent subscriber is useful for debugging or logging, as it can detect
 * misconfigurations in a system's event distribution.
 *
 * @author Cliff Biffle
 * @since 10.0
 */
@ElementTypesAreNonnullByDefault
public class DeadEvent {

  private final Object source;
  private final Object event;

  /**
   * Creates a new DeadEvent.
   *

    GhostCatcher catcher = new GhostCatcher();
    bus.register(catcher);

    bus.post(new DeadEvent(this, EVENT));

    List<DeadEvent> events = catcher.getEvents();
    assertEquals("The explicit DeadEvent should be delivered.", 1, events.size());
    assertEquals("The dead event must not be re-wrapped.", EVENT, events.get(0).getEvent());
  }

  public void testMissingSubscribe() {

    GhostCatcher catcher = new GhostCatcher();
    bus.register(catcher);

    bus.post(new DeadEvent(this, EVENT));

    List<DeadEvent> events = catcher.getEvents();
    assertEquals("The explicit DeadEvent should be delivered.", 1, events.size());
    assertEquals("The dead event must not be re-wrapped.", EVENT, events.get(0).getEvent());
  }

  public void testMissingSubscribe() {

 * {@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.
 *