*
     * @param value the date string to parse
     * @return parsed Date object, or null if parsing fails
     */
    public static Date parseDate(final String value) {
        return parseDate(value, Constants.DATE_OPTIONAL_TIME);
    }

    /**
     * Parses a date string using the specified format.
     *
     * @param value the date string to parse

    @Test
    public void test_parseDate() {
        Date date;

        date = FessFunctions.parseDate("");
        assertNull(date);

        date = FessFunctions.parseDate("2004-04-01T12:34:56.123Z");
        assertEquals("2004-04-01T12:34:56.123Z", FessFunctions.formatDate(date));

        date = FessFunctions.parseDate("2004-04-01T12:34:56Z");
        assertEquals("2004-04-01T12:34:56.000Z", FessFunctions.formatDate(date));

            final Date lastModified = FessFunctions.parseDate(lastModifiedObj.toString());
            if (lastModified != null) {
                return lastModified;
            }
        } else if (lastModifiedObj instanceof final String[] lastModifieds && lastModifieds.length > 0) {
            final Date lastModified = FessFunctions.parseDate(lastModifieds[0]);
            if (lastModified != null) {

                    return !validateDateTimeString(source.get(s));
                }).collect(Collectors.toList()));
    }

    default boolean validateDateTimeString(final Object obj) {
        if (FessFunctions.parseDate(obj.toString()) != null) {
            return true;
        }
        return false;
    }

    String getIndexAdminIntegerFields();

    default Set<String> getIndexAdminIntegerFieldSet() {

     */
    protected Date parseLastModifiedDate(final String value) {
        // Try Apache DateUtils first (handles standard HTTP date formats)
        final Date date = DateUtils.parseDate(value);
        if (date != null) {
            return date;
        }
        // Fallback to custom pattern for non-standard formats (e.g., single-digit day)
        try {