@Override
    public Set<GrokPattern> bulkLoad(Collection<String> patternIds) {
        final DBCursor<GrokPattern> dbCursor = dbCollection.find(DBQuery.in("_id", patternIds));
        return ImmutableSet.copyOf((Iterator<GrokPattern>) dbCursor);
    }
@Test
    @MongoDBFixtures("MongoDbGrokPatternServiceTest.json")
    public void bulkLoadReturnsEmptySetIfGrokPatternsNotFound() {
        final List<String> idList = ImmutableList.of("56250da2d4000000deadbeef");

        final Set<GrokPattern> grokPatterns = service.bulkLoad(idList);
        assertThat(grokPatterns).isEmpty();
    }