*
     * @param key   the key of the feature
     * @param value the value of the feature
     */
    public void addFeature(final String key, final String value) {
        if (StringUtil.isBlank(key) || StringUtil.isBlank(value)) {
            throw new CrawlerSystemException("key or value is null.");
        }

        featureMap.put(key, value);
    }

    /**
     * Adds a property to the extractor.

                        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.");

     * @return the default groups
     */
    protected static String[] getDefaultGroupsAsArray() {
        final String value = ComponentUtil.getFessConfig().getSystemProperty("oic.default.groups");
        if (StringUtil.isBlank(value)) {
            return StringUtil.EMPTY_STRINGS;
        }
        return split(value, ",").get(stream -> stream.filter(StringUtil::isNotBlank).map(String::trim).toArray(n -> new String[n]));
    }

    /**

        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final String slackWebhookUrls = fessConfig.getSlackWebhookUrls();
        if (StringUtil.isBlank(slackWebhookUrls)) {
            return;
        }
        final String body = toSlackMessage(discloser);
        StreamUtil.split(slackWebhookUrls, "[,\\s]").of(stream -> stream.filter(StringUtil::isNotBlank).forEach(url -> {

                }
            }

            String r = realm;
            if (StringUtil.isBlank(realm)) {
                r = AuthScope.ANY_REALM;
            }

            String s = scheme;
            if (StringUtil.isBlank(scheme) || Constants.NTLM.equals(scheme)) {
                s = AuthScope.ANY_SCHEME;
            }

        final String url = DocumentUtil.getValue(doc, fessConfig.getIndexFieldThumbnail(), String.class);
        if (StringUtil.isBlank(form.queryId) || StringUtil.isBlank(url) || !thumbnailSupport) {
            // 404
            throw responseManager.new404("Thumbnail for " + form.docId + " is not found.");
        }

     *
     * @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);
        final String aclPrefix;

     * @param enc the character encoding to use
     * @return the encoded URL
     */
    protected String encodeUrl(final String url, final String enc) {
        if (StringUtil.isBlank(url) || StringUtil.isBlank(enc)) {
            return url;
        }

        final StringBuilder buf = new StringBuilder(url.length() + 100);
        for (final char c : url.toCharArray()) {

                        logger.debug("Loaded KeyMatch Boost Query: {}", boolQuery);
                    }
                    String virtualHost = keyMatch.getVirtualHost();
                    if (StringUtil.isBlank(virtualHost)) {
                        virtualHost = StringUtil.EMPTY;
                    }

        }

        @Test
        @DisplayName("isEmpty and isBlank edge cases")
        void testEmptyAndBlank() throws Exception {
            // No subauthorities
            SID s1 = new SID("S-1-5");
            assertTrue(s1.isEmpty());
            // isBlank will fail if sub_authority is null, so we skip that check for s1

            // All-zero subauthorities