onListen method
void
onListen()
Implementation
void onListen() async {
await controller.addStream(forward!(gqlRequest).handleError((error) {
if(error != null && error is HttpLinkServerException){
Http.Response httpResponse = error.response;
if (httpResponse != null) {
httpResponseHandler(null, httpResponse);
}
}
throw error;
}
));
await controller.close();
}