sS makePostData(Map map) {
  new StringBuilder buf;
  for (Map.Entry<O, O> e : castMapToMapO(map).entrySet()) {
    S key = cast e.getKey();
    O val = e.getValue();
    if (val != null) {
      S value = str(val);
      if (nempty(buf)) buf.append("&");
      buf.append(urlencode(key)).append("=").append(urlencode(/*escapeMultichars*/(value)));
    }
  }
  ret str(buf);
}

sS makePostData(O... params) {
  new StringBuilder buf;
  int n = l(params);
  for (int i = 0; i+1 < n; i += 2) {
    S key = cast params[i];
    O val = params[i+1];
    if (val != null) {
      S value = str(val);
      if (nempty(buf)) buf.append("&");
      buf.append(urlencode(key)).append("=").append(urlencode(/*escapeMultichars*/(value)));
    }
  }
  ret str(buf);

}