code: public String readOnlyTransaction(long singerId, long albumId) {
      // [START readOnlyTransaction]
      String singerColumn = "FirstName";
      String albumColumn = "AlbumTitle";
      String albumTitle = null;
      // ReadOnlyTransaction should be closed to prevent resource leak.
      try (ReadOnlyTransaction txn = dbClient.readOnlyTransaction()) {
        Struct singerRow =
            txn.readRow("Singers", Key.of(singerId), Collections.singleton(singerColumn));
        Struct albumRow =
            txn.readRow("Albums", Key.of(singerId, albumId), Collections.singleton(albumColumn));
        singerRow.getString(singerColumn);
        albumTitle = albumRow.getString(albumColumn);
      }
      // [END readOnlyTransaction]
      return albumTitle;
    }
docs: [VARIABLE my_album_id]