1. @override
dynamic parse(ClassMirror intoType, Request request)

Source

@override
dynamic parse(ClassMirror intoType, Request request) {
  var queryParameters = request.innerRequest.uri.queryParametersAll;
  dynamic value = queryParameters[externalName];
  if (value == null) {
    if (requestHasFormData(request)) {
      value = request.body.asMap()[externalName];
    }
  }

  return convertParameterListWithMirror(value, intoType);
}