code: public Timestamp singleUseReadOnlyTransaction(long singerId) {
      // [START singleUseReadOnlyTransaction]
      String column = "FirstName";
      ReadOnlyTransaction txn = dbClient.singleUseReadOnlyTransaction();
      Struct row = txn.readRow("Singers", Key.of(singerId), Collections.singleton(column));
      row.getString(column);
      Timestamp timestamp = txn.getReadTimestamp();
      // [END singleUseReadOnlyTransaction]
      return timestamp;
    }
docs: [VARIABLE my_singer_id]