class ConfigurationFactory {

    static Set extractPropertyTokens(String sourceDocument) {
        Set propertyTokens = new HashSet();
        Pattern pattern = Pattern.compile("\\$\\{.+?\\}");
        Matcher matcher = pattern.matcher(sourceDocument);
        while (matcher.find()) {
            String token = matcher.group();
            propertyTokens.add(token);
        }
        return propertyTokens;
    }

    private  ConfigurationFactory();

}