class CommonUtils {

    public static String getExtensionFromFileName(String fileName) {
        if (fileName == null) {
            return null;
        }
        for (String multipleExtension : MULTIPLE_FILE_EXTENSIONS) {
            if (fileName.toLowerCase().endsWith(multipleExtension)) {
                int lastIndex = fileName.toLowerCase().lastIndexOf(multipleExtension);
                return fileName.substring(lastIndex + 1);
            }
        }
        return FilenameUtils.getExtension(fileName);
    }

    private  CommonUtils();

}