public void CanFindExplicitTypes()
        {
            var bus = new MessageBus();
            bus.SubscriberFor<TestMessageBase>(m => { });
            bus.SubscriberFor<TestMessageTypeA>(m => { });
            bus.SubscriberFor<TestMessageTypeB>(m => { });

            bus.FindSubscribersOfExplicitType(typeof(TestMessageTypeA))
                .Should().HaveCount(1);
            bus.FindSubscribersOfExplicitType(typeof(TestMessageBase))
                .Should().HaveCount(1);
        }