title: android, how to find out what channel the notification is belong to
body: <p>in the android app when having active notifications it can use</p>
  <pre><code>NotificationManager.getActiveNotifications() 
  </code></pre>
  <p>to get the active notifications.</p>
  <p>If the app configured with multiple notification groups and channels, how to find out what channel the active notification is belong to?</p>