return "Unknown error";
        }

        final Supplier<String> stacktraceString = () -> {
            final StringBuilder sb = new StringBuilder();
            if (StringUtil.isBlank(cause.getMessage())) {
                sb.append(cause.getClass().getName());
            } else {
                sb.append(cause.getMessage());
            }

     * @param path The FTP path to check.
     * @return true if it matches, false otherwise.
     */
    boolean matches(final String path) {
        if (StringUtil.isBlank(path)) {
            return false;
        }

        try {
            final int pos = path.indexOf('/', 6);
            final URI uri = new URI(pos == -1 ? path : path.substring(0, pos));

        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);
    }

        includedDocUrls = fessConfig.getCrawlerDocumentHtmlDefaultIncludeSearchPatterns();
        excludedDocUrls = fessConfig.getCrawlerDocumentHtmlDefaultExcludeSearchPatterns();
        boost = 1.0f;
        if (StringUtil.isBlank(userAgent)) {
            userAgent = fessConfig.getUserAgentName();
        }
        numOfThread = Constants.DEFAULT_NUM_OF_THREAD_FOR_WEB;
        intervalTime = Constants.DEFAULT_INTERVAL_TIME_FOR_WEB;

     * @throws CrawlerSystemException if data deserialization fails
     */
    public Map<String, Object> processRequest(final CrawlingConfig crawlingConfig, final String crawlingInfoId, final String url) {
        if (StringUtil.isBlank(crawlingInfoId)) {
            throw new CrawlingAccessException("sessionId is null.");
        }

     * @param page The HTML page
     * @return The base path for the virtual host
     */
    protected String getVirtualHostBasePath(final String s, final HtmlNext page) {
        return StringUtil.isBlank(s) ? StringUtil.EMPTY : "/" + s;
    }

    /**
     * Gets the virtual host key from the current request.
     * The key is determined by matching HTTP headers against configured virtual hosts.
     *

     * @param version the version of the artifact
     * @return the artifact if found, null otherwise
     */
    public Artifact getArtifact(final String name, final String version) {
        if (StringUtil.isBlank(name) || StringUtil.isBlank(version)) {
            return null;
        }
        for (final Artifact artifact : getAvailableArtifacts(ArtifactType.getType(name))) {

            return LaRequestUtil.getOptionalRequest().map(request -> {
                final String userAgent = request.getHeader("user-agent");
                if (StringUtil.isBlank(userAgent)) {
                    return false;
                }

                return pathMapping.getUAMatcher(userAgent).find();
            }).orElse(false);
        }
        return false;
    }

            }
            builder.endObject();
            return builder;
        }, XContentType.JSON)) {
            message = ((ByteArrayOutputStream) out).toString(Constants.UTF_8);
            if (StringUtil.isBlank(message)) {
                message = "{}";
            }
        } catch (final IOException e) {
            throw new IORuntimeException(e);
        }
    }

    /**
     * Gets the status.

        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);
            }
        }