code: private void initializeArtworkTarget() {
          mThumbnailArtworkTarget = new Target() {
              @Override
              public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
                  mNotificationView.setImageViewBitmap(
                          R.id.simple_sound_cloud_notification_thumbnail, bitmap);
                  mNotificationExpandedView.setImageViewBitmap(
                          R.id.simple_sound_cloud_notification_thumbnail, bitmap);
                  mNotificationManager.notify(NOTIFICATION_ID, buildNotification());
              }
  
              @Override
              public void onBitmapFailed(Drawable errorDrawable) {
  
              }
  
              @Override
              public void onPrepareLoad(Drawable placeHolderDrawable) {
              }
          };
      }
docs: Initialize target used to load artwork asynchronously.