static <A, B> HashMap<A, B> asHashMap(Map<A, B> map) {
  // check for precise type to reject LinkedHashMap
  if (map != null && map.getClass() == HashMap.class) ret (HashMap) map;
  
  HashMap<A, B> m = new HashMap(l(map));
  if (map != null) m.putAll(map);
  ret m;
}