public ImmutableSet<GrantDTO> getForGrantee(GRN grantee) {
        return streamQuery(DBQuery.is(GrantDTO.FIELD_GRANTEE, grantee))
                .collect(ImmutableSet.toImmutableSet());
    }
@Test
    @MongoDBFixtures("grants.json")
    public void getForGrantee() {
        final GRN jane = grnRegistry.newGRN("user", "jane");
        final GRN john = grnRegistry.newGRN("user", "john");

        assertThat(dbService.getForGrantee(jane)).hasSize(3);
        assertThat(dbService.getForGrantee(john)).hasSize(2);
    }