code: public Timestamp singleUseReadOnlyTransactionTimestamp(long singerId) {
      // [START singleUseReadOnlyTransactionTimestamp]
      String column = "FirstName";
      ReadOnlyTransaction txn =
          dbClient.singleUseReadOnlyTransaction(TimestampBound.ofMaxStaleness(10, TimeUnit.SECONDS));
      Struct row = txn.readRow("Singers", Key.of(singerId), Collections.singleton(column));
      row.getString(column);
      Timestamp timestamp = txn.getReadTimestamp();
      // [END singleUseReadOnlyTransactionTimestamp]
      return timestamp;
    }
docs: [VARIABLE my_singer_id]