public static <K, V, T> AbstractGroupExpression<Pair<K, V>, Map<T, V>> map(GroupExpression<K, T> key,
                                                                               Expression<V> value) {
        return map(key, new GOne<V>(value));
    }
Create a new aggregating map expression using a backing LinkedHashMap

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