Hibernate NPE on delete events

.java

@Test
    public void hibernate() throws Exception {
        UUID id = fromString("b80db28f-2e4f-4d18-bb96-6bc5b9b387cb");
        EntityManager entityManager = entityManagerProvider.get();

        ObjectMapper objectMapper = new ObjectMapper();
        doAnswer(new Answer<Void>() {
            @Override
            public Void answer(InvocationOnMock invocation) throws Throwable {
                Object[] args = invocation.getArguments();
                EventEntity<?> entity = (EventEntity<?>) args[0];
                objectMapper.writeValueAsString(entity);
                return null;
            }
        }).when(eventPublisher).publish(any(EventEntity.class));

        CardPlan cardPlan = entityManager.find(CardPlan.class, id);
        entityManager.remove(cardPlan);

        assertFalse(entityManager.contains(cardPlan));

        entityManager.flush();

        verify(eventPublisher, times(1)).publish(any(EventEntity.class));
    }