title: FireBase sending Tokens to server
body: <p>How to send token to server in Firebase cloud messaging.I have tried the following code:</p>
  
  <pre><code>public void onTokenRefresh() {
  // Get updated InstanceID token.
  String refreshedToken = FirebaseInstanceId.getInstance().getToken();
  Log.d(TAG, "Refreshed token: " + refreshedToken);
  
  // TODO: Implement this method to send any registration to your app's servers.
  sendRegistrationToServer(refreshedToken);
  </code></pre>
  
  <p>But there is an error as sendRegistrationToServer(refreshedToken); is not defined.</p>