.containsExactly(
            i1,
            i2,
            i3, // Integer subscribers are dispatched to first.
            s1,
            s2, // Though each integer subscriber dispatches to all string subscribers,
            s1,
            s2, // those string subscribers aren't actually dispatched to until all integer
            s1,
            s2 // subscribers have finished.
            )
        .inOrder();

        .containsExactly(
            i1,
            i2,
            i3, // Integer subscribers are dispatched to first.
            s1,
            s2, // Though each integer subscriber dispatches to all string subscribers,
            s1,
            s2, // those string subscribers aren't actually dispatched to until all integer
            s1,
            s2 // subscribers have finished.
            )
        .inOrder();

 *
 * <p><b>Note:</b> The dispatcher is orthogonal to the subscriber's {@code Executor}. The dispatcher
 * controls the order in which events are dispatched, while the executor controls how (i.e. on which
 * thread) the subscriber is actually called when an event is dispatched to it.
 *
 * @author Colin Decker
 */
@ElementTypesAreNonnullByDefault
abstract class Dispatcher {

  /**

 *
 * <p>The API of this class is designed to make it easy to achieve the following properties
 *
 * <ul>
 *   <li>Multiple events for the same listener are never dispatched concurrently.
 *   <li>Events for the different listeners are dispatched concurrently.
 *   <li>All events for a given listener dispatch on the provided {@link #executor}.
 *   <li>It is easy for the user to ensure that listeners are never invoked while holding locks.

   *         <li>and {@link AbstractInvocationHandler#equals} returns true for the {@link
   *             InvocationHandler} of {@code argument}
   *       </ul>
   *   <li>other method calls are dispatched to {@link #handleInvocation}.
   * </ul>
   */
  @Override
  @CheckForNull
  public final Object invoke(Object proxy, Method method, @CheckForNull @Nullable Object[] args)
      throws Throwable {