subscribePushNotifications

	private void subscribePushNotifications(String inbox ){
		Calendar cal = Calendar.getInstance();
		cal.add(Calendar.HOUR_OF_DAY , 1);
		Subscription sub = new Subscription();
		sub.notificationUrl = "https://ad3309c4.ngrok.io/cats/tickets/notifications";
		sub.changeType = "updated";
		sub.resource = "users/"+inbox+"/messages";
		sub.expirationDateTime = cal;
		sub.clientState = "SecretClientState";

		MSGraphAuthenticationProvider provider = new MSGraphAuthenticationProvider();
		IGraphServiceClient graphClient = GraphServiceClient.builder().authenticationProvider(provider).buildClient();
		graphClient.subscriptions().buildRequest().post(sub, new ICallback<Subscription>() {
			@Override
			public void success(Subscription subscription) {
				System.out.println("Subscription " + subscription);
			}

			@Override
			public void failure(ClientException e) {
				System.out.println("ClientException " + e);
			}
		});
	}