class RepositoryBackedSession {

  public List<String> getAttributeNamesWithValues() {
    ArrayList<String> keys = new ArrayList<>(attrs.size());
    for (Map.Entry<String, Attribute> entry : attrs.entrySet()) {
      if (entry.getValue().value != null) {
        keys.add(entry.getKey());
      }
    }
    return keys;
  }

  public  RepositoryBackedSession(SessionData sessionData, SessionManager manager, SessionFactory factory);
  protected  RepositoryBackedSession(RepositoryBackedSession linked);

}