@Override
    public boolean equals(Object obj) {
      if (!(obj instanceof UnknownLibraryProperties)) return false;
      Element configuration = ((UnknownLibraryProperties)obj).myConfiguration;
      if (configuration == null && myConfiguration == null) return true;
      if (configuration == null || myConfiguration == null) return false;
      return JDOMUtil.areElementsEqual(myConfiguration, configuration);
    }
@Override
    public boolean equals(Object obj)