public Collection<InvalidProperty> process(Map<String, String> properties) {
    List<InvalidProperty> result = new Vector<InvalidProperty>();

    final String files = properties.get(XmlTestConstants.SETTINGS_FILES);
    final String project = properties.get(XmlTestConstants.SETTINGS_PROJECT);

    if (PropertiesUtil.isEmptyOrNull(project) && PropertiesUtil.isEmptyOrNull(files)) {
      result.add(
          new InvalidProperty(
              XmlTestConstants.SETTINGS_FILES, "Files or project option must be specified"));
    }

    return result;
  }