@Override
  public boolean validate() throws ConfigurationException {
    calcDuplicates();
    if (!duplicateNames.isEmpty()) {
      throw new ConfigurationException(
        EclipseBundle.message("duplicate.names.found.import.error.message", StringUtil.join(duplicateNames, ",")),
        EclipseBundle.message("unable.to.proceed.import.title"));
    }
    return super.validate();
  }
@Override
  public boolean validate()