title: Can FCM notification on Android overwrite previous one?
body: <p>I'm using FCM to send notifications to Android devices. When the app is in background, if I send 10 notifications, the devices will show up 10 entries on the notification bar.</p>
  
  <p>I want FCM to make only one entry on notification bar, i.e. the newer one will overwrite old ones. I don't find a key to set this at <a href="https://firebase.google.com/docs/cloud-messaging/http-server-ref#downstream" rel="noreferrer">https://firebase.google.com/docs/cloud-messaging/http-server-ref#downstream</a>.</p>
  
  <p>Is there a way to do, or it is impossible? Thanks.</p>