}

    @Override
    public void afterTask(final Closure closure) {
        notifyListenerRegistration("TaskExecutionGraph.afterTask", closure);
        taskListeners.add(new ClosureBackedMethodInvocationDispatch("afterExecute", closure));
    }

    @Override
    public void afterTask(final Action<Task> action) {
        notifyListenerRegistration("TaskExecutionGraph.afterTask", action);

        }
        def action = Mock(Action)

        final Task a = task("a")
        final Task b = task("b")

        when:
        taskGraph.afterTask(closure)
        taskGraph.afterTask(action)
        taskExecutionListeners.source.afterExecute(a, a.state)
        taskExecutionListeners.source.afterExecute(b, b.state)

        then:
        1 * closure.call(a)