// Add defensive null/blank checks
        if (StringUtil.isBlank(username) || StringUtil.isBlank(password)) {
            if (logger.isDebugEnabled()) {
                logger.debug("Login failed: username or password is blank");
            }
            return OptionalEntity.empty();
        }

        if (StringUtil.isBlank(fessConfig.getLdapProviderUrl()) || !validate()) {

        if (list == null) {
            final String value = getSystemProperty(Constants.DEFAULT_SORT_VALUE_PROPERTY);
            if (StringUtil.isBlank(value)) {
                list = Collections.emptyList();
            } else {
                final Set<String> keySet = new HashSet<>();

                        final String userCode = userInfoHelper.getUserCode();

                        if (StringUtil.isBlank(userCode)) {
                            throw new WebApiException(HttpServletResponse.SC_BAD_REQUEST, "No user session.");
                        }
                        if (StringUtil.isBlank(favoriteUrl)) {
                            throw new WebApiException(HttpServletResponse.SC_BAD_REQUEST, "URL is null.");

        String value = ComponentUtil.getFessConfig().getSystemProperty(ENTRAID_DEFAULT_GROUPS);
        if (StringUtil.isBlank(value)) {
            value = ComponentUtil.getFessConfig().getSystemProperty(AAD_DEFAULT_GROUPS);
        }
        if (StringUtil.isBlank(value)) {
            return Collections.emptyList();
        }

        if (xpath == null) {
            xpath = fessConfig.getCrawlerDocumentHtmlCanonicalXpath();
        }
        if (StringUtil.isBlank(xpath)) {
            return null;
        }
        final String canonicalUrl = getSingleNodeValue(document, xpath, node -> node);
        if (StringUtil.isBlank(canonicalUrl)) {
            return null;
        }
        return normalizeCanonicalUrl(responseData.getUrl(), canonicalUrl);
    }

        String title = DocumentUtil.getValue(document, fessConfig.getIndexFieldTitle(), String.class);
        if (StringUtil.isBlank(title)) {
            title = DocumentUtil.getValue(document, fessConfig.getIndexFieldFilename(), String.class);
            if (StringUtil.isBlank(title)) {
                title = DocumentUtil.getValue(document, fessConfig.getIndexFieldUrl(), String.class);
            }
        }

                searchResult = searchByUrl(intentResult.getDocumentUrl());
            } else {
                final String query = StringUtil.isBlank(intentResult.getQuery()) ? userMessage : intentResult.getQuery();
                searchResult = searchWithQueryAndMetadata(query, safeFields, safeExtraQueries);

                // Fallback: regenerate query if no results

     *
     * @param text the text to strip HTML tags from
     * @return the text without HTML tags
     */
    protected String stripHtmlTags(final String text) {
        if (StringUtil.isBlank(text)) {
            return text;
        }
        return text.replaceAll("<[^>]+>", "");
    }

    /**
     * Sanitizes document content by escaping delimiter-like sequences

                        m);
            }

            for (int i = 0, n = m.getModules().size(); i < n; i++) {
                String module = m.getModules().get(i);
                if (StringUtils.isBlank(module)) {
                    addViolation(
                            problems,
                            Severity.ERROR,
                            Version.BASE,

     * and sitemap information.
     *
     * @param url The URL to process robots.txt for
     */
    protected void processRobotsTxt(final String url) {
        if (StringUtil.isBlank(url)) {
            throw new CrawlerSystemException("HTTP URL is null or empty. Cannot process robots.txt without a valid URL.");
        }

        if (robotsTxtHelper == null || !robotsTxtHelper.isEnabled()) {