close method
Close the request for input. Returns the value of done.
Implementation
@override
Future<HttpClientResponse> close() {
  return _httpClientRequest.close().then(
      (response) => _wrapResponse(
          response, _httpClientRequest, this.timestamp, traceData),
      onError: (dynamic err) {
    NewrelicMobile.instance.recordError(err, StackTrace.current);
    throw err;
  });
}