How to send FCM message from Appengine server on cloud code works local server - google-app-engine

Question

How to do it in cloud AppEngine without billing.
I am able to get Token from Javascript but sending messages to the server for notification. Create JSON object for downstream data/notification. On the server saying billing for the socket.
private void localappengine(HttpServletResponse response, String ENDPOINT_URL) throws IOException {
HttpClient client = new DefaultHttpClient();
Log.info("after client");
HttpPost post = new HttpPost(ENDPOINT_URL);
String deviceToken="cthG-hesotM:APA91bGg_tLg7TqvpY4aAvzHpyBK2mTTOT2KgO94tDFcLGPakcS9vmXkYEIe4Vh0Mo5ka1COfaXarUEJGWyqDdmVi_kujUfKDtE4C30eZwkPQATXnFrDPJxHxd8iouwsWuRcAk-ZYe_4";
PrintWriter out=response.getWriter();
response.getWriter().println("Hello from myservlet " );
// Create JSON object for downstream data/notification
JSONObject mainNotificationJsonObj = new JSONObject();
JSONObject outerBaseJsonObj = new JSONObject();
try {
// Notification payload has 'title' and 'body' key
mainNotificationJsonObj.put("title", "testing message");
mainNotificationJsonObj.put("body", "Hello I sent it");
// This will be used in case of both 'notification' or 'data' payload
outerBaseJsonObj.put("to", deviceToken);
// Set priority of notification. For instant chat setting
// high will
// wake device from idle state - HIGH BATTERY DRAIN
//outerBaseJsonObj.put(PRIORITY_KEY, PRIORITY_HIGH);
// Specify required payload key here either 'data' or
// 'notification'. We can even use both payloads in single
// message
outerBaseJsonObj.put("notification", mainNotificationJsonObj);
} catch (JSONException e) {
e.printStackTrace();
}
Log.info("before entity");
// Setup http entity with json data and 'Content-Type' header
StringEntity requestEntity = new StringEntity(outerBaseJsonObj.toString());
//(outerBaseJsonObj.toString(), APPLICATION_JSON);
String FIREBASE_SERVER_KEY= "key=AAAA6nN2BxI:APA91bHYotXML0siwL0Pm0LK5iXQ9Ik1kQtdB1ALbJrm5kseUk2zS5gJs6AMHVsX86exEE-JFsIF962YNY1yRyl3yFxGCyMBAH4OKwTn8Ff6vcd6vJMVXutNlP99X8AtOsW8_JIBkyEl";
// Setup required Authorization header
post.setHeader("Authorization", FIREBASE_SERVER_KEY);
post.setHeader("Content-Type", String.valueOf(APPLICATION_JSON));
Log.info("after header");
// Pass setup entity to post request here
post.setEntity(requestEntity);
// Execute apache http client post response
HttpResponse fcmResponse = client.execute(post);
Log.info("after client execute");
// Get status code from FCM server to debug error and success
System.out.println("RESPONSE_CODE" + fcmResponse.getStatusLine().getStatusCode());
// Get response entity from FCM server and read throw lines
BufferedReader rd = new BufferedReader(new InputStreamReader(fcmResponse.getEntity().getContent()));
StringBuffer result = new StringBuffer();
String line = "";
while ((line = rd.readLine()) != null) {
result.append(line);
}
if (response != null) {
// Print out the response to webpage
PrintWriter out1;
out1 = response.getWriter();
out1.println(result);
System.out.println("This is Result - " + result);
}
}