code: public static <K, V> AbstractGroupExpression<Pair<K, V>,Map<K, V>> map(Expression<K> key,
                                                                             Expression<V> value) {
          return GMap.createLinked(QPair.create(key, value));
      }
docs: 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