@Test
void whenSameClassSubscribesTwiceToP2P_thenException() {

    validator.validate(new DummySubscriberA(), ImmutableList.of(DummyP2PNotification.class));
    IllegalStateException e = Assertions.assertThrows(IllegalStateException.class,
            () -> validator.validate(new DummySubscriberA(), ImmutableList.of(DummyP2PNotification.class)));
    Assertions.assertTrue(e.getMessage().contains(DummyP2PNotification.class.getSimpleName()));
}