title: Notification background with grey square
body: <p>When the notif is displayed, the icon is showed. But when I expand the notification menu, it's a grey icon.</p>
  
  <p>My manifest :</p>
  
  <pre><code> &lt;meta-data
          android:name="com.google.firebase.messaging.default_notification_icon"
          android:resource="@drawable/ic_notification" /&gt;
  
      &lt;meta-data
          android:name="com.google.firebase.messaging.default_notification_color"
          android:resource="@android:color/transparent" /&gt;
  </code></pre>
  
  <p>For exemple, here in this screenshot, the icon is displayed (the green one) :</p>
  
  <p><a href="https://i.stack.imgur.com/G4j5T.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/G4j5T.jpg" alt="enter image description here"></a></p>
  
  <p>But then :</p>
  
  <p><a href="https://i.stack.imgur.com/EwmXF.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EwmXF.jpg" alt="enter image description here"></a></p>