static Map paramsToMap_withNulls(O... params) {
  int n = l(params);
  if (l(params) == 1 && params[0] instanceof Map) ret (Map) params[0];
  new LinkedHashMap map;
  for (int i = 0; i+1 < n; i += 2)
    map.put(params[i], params[i+1]);
  ret map;
}