*
     * @param value the string that may contain email addresses
     * @return string with email addresses replaced by masked pattern
     */
    public static String maskEmail(final String value) {
        if (value == null) {
            return StringUtil.EMPTY;
        }
        return EMAIL_ADDRESS_PATTERN.matcher(value).replaceAll("******@****.***");
    }

        String value;

        value = FessFunctions.maskEmail(null);
        assertEquals("", value);

        value = FessFunctions.maskEmail("");
        assertEquals("", value);

        value = FessFunctions.maskEmail("aaa bbb ccc");
        assertEquals("aaa bbb ccc", value);

        value = FessFunctions.maskEmail("******@****.***");
        assertEquals("******@****.***", value);