} catch (Exception e) {
            fail("sendToSlack() should not throw an exception with blank URLs: " + e.getMessage());
        }
    }

    @Test
    public void test_sendToSlack_withNullWebhookUrls() {
        // Setup mock configuration with null webhook URLs
        ComponentUtil.setFessConfig(new MockFessConfig() {
            @Override
            public String getSlackWebhookUrls() {

            if (StringUtil.isNotBlank(getIncludedDocUrls())) {
                final List<Pattern> urlPatterList = new ArrayList<>();
                final String[] urls = getIncludedDocUrls().split("[\r\n]");
                for (final String u : urls) {
                    final String v = systemHelper.normalizeConfigPath(u);
                    if (StringUtil.isNotBlank(v)) {

import org.codelibs.fess.crawler.service.UrlQueueService;

import jakarta.annotation.Resource;

/**
 * The Crawler class is the main class for web crawling. It manages the crawling process,
 * including adding URLs to the queue, filtering URLs, managing crawler threads,
 * and handling the overall crawling lifecycle.
 *
 * <p>It implements the Runnable interface to be executed in a separate thread,

        this.updatedTime = value;
    }

    public String getUrls() {
        checkSpecifiedProperty("urls");
        return convertEmptyToNull(urls);
    }

    public void setUrls(String value) {
        registerModifiedProperty("urls");
        this.urls = value;
    }

    public String getUserAgent() {
        checkSpecifiedProperty("userAgent");

    /** XML element name for start URLs configuration. */
    protected static final String START_URLS = "start_urls";

    /** XML element name for good (included) URLs configuration. */
    protected static final String GOOD_URLS = "good_urls";

    /** XML element name for bad (excluded) URLs configuration. */
    protected static final String BAD_URLS = "bad_urls";

        }
    }

    /**
     * Extracts anchor URLs from the given object and converts them to RequestData objects.
     * The input object can be either a single string or a list of strings representing URLs.
     *
     * @param obj the object containing anchor URLs (String or List of Strings)
     * @return a set of RequestData objects for the anchor URLs, or null if no valid URLs found
     */

    }

    private static final Logger logger = LogManager.getLogger(WebFsIndexHelper.class);

    private static final String DISABLE_URL_ENCODE = "#DISABLE_URL_ENCODE";

    /**
     * Maximum number of URLs to access during crawling.
     */
    protected long maxAccessCount = Long.MAX_VALUE;

    /**
     * Interval time in milliseconds between crawling executions.
     */

            logHelper.log(key, objs);
        }
    }

    /**
     * Runs the crawling process in a separate thread.
     * This method fetches URLs from the queue, accesses content, processes responses,
     * and extracts child URLs until the crawling process is done or no more URLs are available.
     */
    @Override
    public void run() {
        log(logHelper, LogType.START_THREAD, crawlerContext);

        for (int i = 0; i < threadCount; i++) {
            assertNull(exceptions[i], "Thread " + i + " threw exception");
        }

        // Verify all URLs were added
        synchronized (mockCallback) {
            assertEquals("All URLs should be added", threadCount * urlsPerThread, callback.deleteUrlList.size());
        }
    }

    /**
     * Test concurrent reads from deleteUrlList while synchronized.

    }

    /**
     * Retrieves a list of URLs that should be excluded from crawling based on failure counts.
     * URLs are excluded if they have failed more than the configured failure count threshold.
     * URLs can also be filtered by failure type using a regular expression pattern.
     *
     * @param configId the configuration ID to get excluded URLs for