assertEquals("", StringUtil.substringToLast("abc", "c"));
        assertEquals("c", StringUtil.substringToLast("abc", "b"));
        assertEquals("c", StringUtil.substringToLast("abcbc", "b"));
        assertEquals("abc", StringUtil.substringToLast("abc", ""));
        assertEquals("abc", StringUtil.substringToLast("abc", null));
        assertEquals("abc", StringUtil.substringToLast("abc", "dddd"));
    }

    /**

     *
     * @param str
     *            the string
     * @param separator
     *            the separator
     * @return the resulting string
     */
    public static String substringToLast(final String str, final String separator) {
        if (isEmpty(str) || isEmpty(separator)) {
            return str;
        }
        final int pos = str.lastIndexOf(separator);
        if (pos == -1) {