public static <K extends Comparable<? super K>, V extends Comparable<? super V>> AbstractGroupExpression<Pair<K, V>, SortedSetMultimap<K, V>> sortedSetMultimap(Expression<K> key,
                                                                                                                                                                    Expression<V> value) {
        return GMultimap.createSorted(QPair.create(key, value));
    }
Create a new aggregating map expression using a backing TreeMap

@param key key for the map entries
@param value value for the map entries
@return wrapper expression
querydsl-guava/src/main/java/com/querydsl/core/group/guava/GuavaGroupBy.java