code: public static String formURLEncodeMap(Map<String, String> map) {
          Preconditions.checkNotNull(map, "Cannot url-encode a null object");
  
          return (map.size() <= 0) ? EMPTY_STRING : doFormUrlEncode(map);
      }
docs: Turns a map into a form-urlencoded string
  
  @param map any map
  @return form-url-encoded string