code: public void markAsViewed(int notificationId) {
  		getResourceFactory()
  				.getApiResource("/notification/" + notificationId + "/viewed")
  				.entity(new Empty(), MediaType.APPLICATION_JSON_TYPE).post();
  	}
docs: Mark the notification as viewed. This will move the notification from the
  inbox to the viewed archive.
  
  @param notificationId
  The id of the notification