public int hashCode() {
    int result;
    result = Long.hashCode(myRevision);
    result = 31 * result + (myAuthor != null ? myAuthor.hashCode() : 0);
    result = 31 * result + (myDate != null ? myDate.hashCode() : 0);
    result = 31 * result + (myMessage != null ? myMessage.hashCode() : 0);
    return result;
  }
public int hashCode()