title: NotificationCompat - how to add action without icon?
body: <pre><code>NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this, channelId)
                  .setSmallIcon(R.drawable.schedule)
                  .addAction(R.drawable.icon,"action test",pi)
                  .setStyle(new NotificationCompat.BigTextStyle().bigText(body))
                  .setContentTitle(title)
                  .setContentText(body);
  </code></pre>
  
  <p>Above code creates notification and adds one action (button) to it. I want my button to be without icon displayed, but I don't know how to do that, because <code>icon</code> in parameter <code>addAction</code>  is required and not nullable.</p>
  
  <p>Is it even possible to add action button to notification without any icon (btw, icons on action buttons seems to be not even shown on Nougat an Oreo).</p>