Collection attributes indexed with [any] causes wrong SqlQuery results if first data inserted to map has no value for the attribute or the collection is empty

[gokhanoner]

Please see: https://stackoverflow.com/questions/54095774/hazelcast-not-working-correctly-with-sqlpredicate-and-index-on-optional-field

The problem here, when initializing TypeConverter inside the index, if the indexed property is in a collection and when

• the collection is null
• the collection is empty
• the collection is not empty but the attribute is null for all entries

Then QueryableEntry.getConverter returns IDENTITY_CONVERTER. This causes wrong converter type initialization and causing SqlPredicate to return wrong results.

Suggested Fix:

from getConverter method:

 else {
            AttributeType attributeType = extractAttributeType(attributeName, attribute);
            return attributeType == null ? IDENTITY_CONVERTER : attributeType.getConverter();
        }

The only case attributeType is null is when the attribute is the type of MultiResult and either all values in it is null or it is an instance of ImmutableMultiResut which means Collection itself is null or empty. In this case, we should return NULL_CONVERTER instead of IDENTITY_CONVERTER so that index can continue to find correct TypeConverter with next entry.

Simple reproducer:

    public static void main(String[] args) {
        Config config = new Config();
        final MapConfig mapConfig = config.getMapConfig("data");
        mapConfig.addMapIndexConfig(new MapIndexConfig("nested[any].number", false));

        HazelcastInstance instance = Hazelcast.newHazelcastInstance(config);

        IMap<Integer, Data> map = instance.getMap("data");

        Data data1 = new Data(Collections.emptyList());
        Data data2 = new Data(Arrays.asList(new SubData(1)));

        Predicate equalPredicate = Predicates.equal("nested[any].number", 1);
        Predicate sqlPredicate = new SqlPredicate("nested[any].number=1");


        map.put(1, data1);
        map.put(2, data2);

        Collection<Data> equalResults = map.values(equalPredicate);
        Collection<Data> sqlResults = map.values(sqlPredicate);

        assertEquals(1, equalResults.size()); // contains "1"
        assertEquals(1, sqlResults.size());   // --> this fails, it returns en empty list
    }

    static class Data implements Serializable {
        private final List<SubData> nested;

        public Data(List<SubData> nested) {
            this.nested = nested;
        }

        public List<SubData> getNested() {
            return nested;
        }
    }

    static class SubData implements Serializable {
        private final Integer number;

        public SubData(Integer number) {
            this.number = number;
        }

        public Integer getNumber() {
            return number;
        }
    }