}

  @Override
  public boolean containsValue(Object value) {
    for (Timestamped<V> val : cachingHashMap.values()) {
      if (val.getValue().equals(value)) {
        if (!isExpired(val)) {
          return true;
        }
      }
    }
    return false;
  }

  private boolean isExpired(Timestamped<V> stamped) {