// 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 the virtual host is blank or null, returns an empty string.
     *
     * @param entity the RelatedQuery entity to extract the host key from
     * @return the virtual host key, or empty string if blank or null
     */
    protected String getHostKey(final RelatedQuery entity) {
        final String key = entity.getVirtualHost();
        return StringUtil.isBlank(key) ? StringUtil.EMPTY : key;
    }

     *
     * @param value the permission string to encode
     * @return the encoded permission string, or null if the input is blank or invalid
     */
    public String encode(final String value) {
        if (StringUtil.isBlank(value)) {
            return null;
        }

        String permission = value.trim();
        String lower = permission.toLowerCase(Locale.ROOT);

        return true;
    }

    /**
     * Returns true if the string is not blank.
     *
     * @param str
     *            the string to check
     * @return {@literal true} if the string is not blank
     * @see #isBlank(String)
     */
    public static boolean isNotBlank(final String str) {
        return !isBlank(str);
    }

    /**

    }

    /**
     * Test getAnchorSet with blank string
     */
    @Test
    public void test_getAnchorSet_withBlankString() {
        FessCrawlerThread crawlerThread = new FessCrawlerThread();

        Set<RequestData> result = crawlerThread.getAnchorSet("");
        assertNull(result, "getAnchorSet should return null for blank string");

        result = crawlerThread.getAnchorSet("   ");

    }

    /**
     * Checks whether the SID is blank (all sub-authorities zero).
     *
     * @return whether the SID is blank (all sub-authorities zero)
     */
    public boolean isBlank() {
        boolean blank = true;
        for (final int sub : this.sub_authority) {
            blank = blank && sub == 0;
        }
        return blank;
    }

    /**
     *
     * @return domain SID

     *
     * @param u the URL string to extract host from
     * @return the host name, or empty string if URL is blank, or unknown hostname if parsing fails
     */
    default String getHost(final String u) {
        if (StringUtil.isBlank(u)) {
            return StringUtil.EMPTY; // empty
        }

        String url = u;
        final String originalUrl = url;

        this.relatedContentMap = relatedContentMap;
        return relatedContentMap.size();
    }

    /**
     * Extracts the virtual host key from a RelatedContent entity.
     * If the virtual host is blank or null, returns an empty string.
     * This key is used to organize related content by virtual host.
     *
     * @param entity the RelatedContent entity to extract the host key from

                return true;
            }
        }
        // Also allow "/" as a valid path (used in loadJspFileNameItems for blank keys)
        return "/".equals(path);
    }

    // ===================================================================================
    //                                                                        Small Helper

     * @param defaultValue the default value to return if key is not found or value is blank
     * @return the value from the map or the default value
     */
    private String getValueFromMap(final Map<String, String> dataMap, final String key, final String defaultValue) {
        final String value = dataMap.get(key);
        if (StringUtil.isBlank(value)) {
            return defaultValue;
        }
        return value;
    }