Querying of java.util.Map

[bosbeles]

if(rsql != null) {
QueryConversionPipeline pipeline = QueryConversionPipeline.defaultPipeline();
Condition condition = pipeline.apply(rsql, Notification.class);
Criteria criteria = condition.query(new MongoVisitor());
query.addCriteria(criteria);
}

Suppose you have a class Notification.class with a field:
private Map<String, Object> data;
And you're querying "data.category==cat-1" where category is a key of a map.
Then EntityFieldTypeResolver throws a null pointer exception.
I changed its apply method as follows:
@OverRide
public Class apply(FieldPath path, Class root) {
String[] splitField = path.asKey().split("\.", 2);
Field field = getField(root, splitField[0], true);
if(field == null) {
return Object.class;
}

    if(splitField.length == 1) {

        return normalize(field);
    } else {
        return apply(new FieldPath(splitField[1]), normalize(field));
    }
} 

But is this the right approach? Is it possible to add map inside maps etc. a more generic approach I mean.

[emreesirik]

is there any idea? why we can not query for Map attributes