public Set<ContentPackInstallation> findByContentPackId(ModelId id) {
        final DBQuery.Query query = DBQuery.is(ContentPackInstallation.FIELD_CONTENT_PACK_ID, id);
        try (final DBCursor<ContentPackInstallation> installations = dbCollection.find(query)) {
            return ImmutableSet.copyOf((Iterator<ContentPackInstallation>) installations);
        }
    }
@Test
    @MongoDBFixtures("ContentPackInstallationPersistenceServiceTest.json")
    public void findByContentPackId() {
        final ModelId id = ModelId.of("4e3d7025-881e-6870-da03-cafebabe0001");
        final Set<ContentPackInstallation> contentPacks = persistenceService.findByContentPackId(id);

        assertThat(contentPacks)
                .hasSize(2)
                .allSatisfy(contentPackInstallation -> assertThat(contentPackInstallation.contentPackId()).isEqualTo(id))
                .anySatisfy(contentPackInstallation -> assertThat(contentPackInstallation.id()).isEqualTo(new ObjectId("5b4c935b4b900a0000000001")))
                .anySatisfy(contentPackInstallation -> assertThat(contentPackInstallation.id()).isEqualTo(new ObjectId("5b4c935b4b900a0000000002")));
    }