title: NotificationCompat with API 26
body: <p>I dont see any information about how to use NotificationCompat with Android O's <code>Notification Channels</code></p>
  
  <p>I do see a new Constructor that takes a <code>channelId</code> but how to take a Compat notification and use it in a NotificationChannel since <code>createNotificationChannel</code> takes a <code>NotificationChannel</code> object</p>