toQueryString method Null safety

String toQueryString()

toQueryString Returns the String built with the Map keys and values ready to be used as an HTTP GET query String.

Implementation

String toQueryString() {
  String ret = "";
  forEach((key, value) {
    if (ret.isNotEmpty) {
      ret += "&";
    }
    ret += key.toString() + "=" + value.toString();
  });
  return (ret);
}