public Optional<ContentPack> findByIdAndRevision(ModelId id, int revision) {
        final DBQuery.Query query = DBQuery.is(Identified.FIELD_META_ID, id).is(Revisioned.FIELD_META_REVISION, revision);
        return Optional.ofNullable(dbCollection.findOne(query));
    }
@Test
    @MongoDBFixtures("ContentPackPersistenceServiceTest.json")
    public void findByIdAndRevisionWithInvalidId() {
        final Optional<ContentPack> contentPack = contentPackPersistenceService.findByIdAndRevision(ModelId.of("does-not-exist"), 2);

        assertThat(contentPack).isEmpty();
    }