@Override
  public int hashCode() {
    int result = key != null ? key.hashCode() : 0;
    result = 31 * result + (int) (timestamp ^ (timestamp >>> 32));
    result = 31 * result + (int) (seqNum ^ (seqNum >>> 32));
    return result;
  }
The store key used in the {@link TimeSeriesStore} to uniquely identify a row.
samza-core/src/main/java/org/apache/samza/operators/impl/store/TimeSeriesKey.java