@Override
    public GroupingLevel clone() {
        GroupingLevel obj = (GroupingLevel)super.clone();
        if (classify != null) {
            obj.classify = classify.clone();
        }
        if (filter != null) {
            obj.filter = filter.clone();
        }
        obj.collect = collect.clone();
        return obj;
    }
<p>Tell if ordering will need results collected in children.</p>

@return If deeper resultcollection is needed.
searchlib/src/main/java/com/yahoo/searchlib/aggregation/GroupingLevel.java