docs: public static Map mapValues(Mapper mapper, Map map, boolean includeNull) {
          HashMap h = new HashMap();
          for (Object e : map.keySet()) {
              Map.Entry entry = (Map.Entry) e;
              Object v = entry.getValue();
              Object o = mapper.map(v);
              if (includeNull || o != null) {
                  h.put(entry.getKey(), o);
              }
          }
          return h;
      }