public static <K, V> AbstractGroupExpression<Pair<K, V>, SortedSetMultimap<K, V>> sortedSetMultimap(Expression<K> key,
                                                                                                        Expression<V> value,
                                                                                                        Comparator<? super K> keyComparator,
                                                                                                        Comparator<? super V> valueComparator) {
        return GMultimap.createSorted(QPair.create(key, value), keyComparator, valueComparator);
    }
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 keyComparator comparator for the created TreeMap instances
@param valueComparator comparator for the created TreeMap instances
@return wrapper expression
querydsl-guava/src/main/java/com/querydsl/core/group/guava/GuavaGroupBy.java