docs: public static Map makeMap(Mapper mapper, Enumeration en, boolean includeNull) {
          HashMap h = new HashMap();
          for (; en.hasMoreElements();) {
              Object k = en.nextElement();
              Object v = mapper.map(k);
              if (includeNull || v != null) {
                  h.put(k, v);
              }
          }
          return h;
      }