title: Use Firebase Topic Messages with Android Notification Channels
body: <p>I have an app with different notification types it can receive (for example <code>News</code> and <code>Podcast</code>). Currently it has two simple switches where the user can enable and disable those different notification types. It works by just subscribing and unsubscribing from the corresponding Firebase Topic for the type. The clear advantage is that the device only receives the notification the user wants and does not have to filter them locally => battery and data efficient.</p>
  
  <p>Problem is, I want to combine it with the new android O notification channels. Am I right to assume that the only way is to just subscribe to all topics in Firebase and have the user manually disable unwanted ones in the android settings? </p>
  
  <p>Is there a better way that saves more battery life (by not receiving all notifications)? </p>