public int deleteById(ModelId id) {
        final DBQuery.Query query = DBQuery.is(Identified.FIELD_META_ID, id);
        final WriteResult<ContentPack, ObjectId> writeResult = dbCollection.remove(query);
        return writeResult.getN();
    }
@Test
    @MongoDBFixtures("ContentPackPersistenceServiceTest.json")
    public void deleteById() {
        final int deletedContentPacks = contentPackPersistenceService.deleteById(ModelId.of("dcd74ede-6832-4ef7-9f69-deadbeef0000"));
        final Set<ContentPack> contentPacks = contentPackPersistenceService.loadAll();

        assertThat(deletedContentPacks).isEqualTo(3);
        assertThat(contentPacks)
                .hasSize(2)
                .noneMatch(contentPack -> contentPack.id().equals(ModelId.of("dcd74ede-6832-4ef7-9f69-deadbeef0000")));
    }