code: private String getExtraArtistName() {
          Bundle extras = getIntent().getExtras();
          if (extras == null || !extras.containsKey(BUNDLE_KEY_ARTIST_NAME)) {
              return ""; // activity started through the notification pending intent
          }
          return extras.getString(BUNDLE_KEY_ARTIST_NAME);
      }
docs: Used to retrieve the artist name for the bundle.
  
  @return artist name.