public static <K, V, T> AbstractGroupExpression<Pair<K, V>, SortedMap<T, V>> sortedMap(GroupExpression<K, T> key,
                                                                                           Expression<V> value,
                                                                                           Comparator<? super T> comparator) {
        return sortedMap(key, new GOne<V>(value), comparator);
    }
Create a new aggregating map expression using a backing TreeMap using the given comparator

@param key key for the map entries
@param value value for the map entries
@param comparator comparator for the created TreeMap instances
@return wrapper expression
querydsl-core/src/main/java/com/querydsl/core/group/GroupBy.java