title: Firebase instance id: deprecation of getId() in 21.0.0
body: <p>With the recent release of FirebaseInstanceId and FirebaseCloudMessaging (<code>21.0.0</code>) Firebase has deprecated <code>iid</code> package and both <code>getToken()</code> and <code>getId()</code> methods are now deprecated.</p>
  <p>According to the <a href="https://firebase.google.com/support/release-notes/android#iid_v21-0-0" rel="noreferrer"><strong>Firebase release note</strong></a> the method <code>getToken()</code> is moved to <code>FirebaseMessaging</code></p>
  <p>Before:</p>
  <pre><code>FirebaseInstanceId.getInstance().getToken()
  </code></pre>
  <p>After:</p>
  <pre><code>FirebaseMessaging.getInstance().getToken()
  </code></pre>
  <p>Which gives use the <code>fcmToken</code>, but to retrieve <strong>instance id</strong>, there's no method available in FirebaseMessaging nor FirebaseInstanceId.</p>
  <hr />
  <p><strong>So</strong>, Is <code>instance_id</code> considered a useless id and should no longer be used? or is there a replacement for this?</p>