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