public void test_getClient_null() {
        String url;
        CrawlerClient client;

        url = null;
        client = clientFactory.getClient(url);
        assertNull(client);

        url = "";
        client = clientFactory.getClient(url);
        assertNull(client);

        url = " ";
        client = clientFactory.getClient(url);
        assertNull(client);
    }

/**
 * Service interface for managing URL filters.
 * Provides methods to add and remove include/exclude URL filters,
 * as well as retrieve the patterns of these filters.
 */
public interface UrlFilterService {

    /**
     * Adds a URL to the include filter list for the specified session.
     *
     * @param sessionId the ID of the session for which the URL filter is being added

        sessionMap.clear();
    }

    /**
     * Returns a list of access results for the specified URL across all sessions.
     * @param url the URL to search for
     * @return the list of access results for the URL
     */
    public synchronized List<AccessResultImpl<Long>> getAccessResultList(final String url) {
        final List<AccessResultImpl<Long>> acList = new ArrayList<>();

                    }
                });
    }

    /**
     * Adds an include URL filter for the specified session.
     *
     * @param sessionId The session ID.
     * @param url The URL pattern to include.
     */
    @Override
    public void addIncludeUrlFilter(final String sessionId, final String url) {
        final OpenSearchUrlFilter esUrlFilter = new OpenSearchUrlFilter();

            file.deleteOnExit();
            fileTransformer.setPath(file.getAbsolutePath());
            crawler.addUrl(url);
            crawler.crawlerContext.setMaxAccessCount(maxCount);
            crawler.crawlerContext.setNumOfThread(numOfThread);
            crawler.urlFilter.addInclude(url + ".*");
            final String sessionId = crawler.execute();
            assertEquals(maxCount, dataService.getCount(sessionId));

                }
            }
        }
    }

    /**
     * Generate a path from a url.
     *
     * @param url URL
     * @return path File path
     */
    protected String getFilePath(final String url) {
        return url.replaceAll("/+", "/")
                .replace("./", "")
                .replace("../", "")
                .replaceAll("/$", "/index.html")

            }
        }
    }

    /**
     * Gets the appropriate crawler client for the given URL.
     * @param url The URL to get a client for.
     * @return The crawler client.
     */
    protected CrawlerClient getClient(final String url) {
        return clientFactory.getClient(url);
    }

    /**
     * Checks if the content has been updated since the last crawl.

 * It converts Unicode domain names to ASCII Compatible Encoding (ACE) using the
 * {@link java.net.IDN} class.
 *
 * <p>This class allows setting a custom flag for the IDN conversion and a custom
 * encoding for URL decoding.</p>
 *
 * <p>Example usage:</p>
 * <pre>
 * {@code
 * IdnDnsResolver resolver = new IdnDnsResolver();
 * resolver.setFlag(IDN.ALLOW_UNASSIGNED);
 * resolver.setEncoding("UTF-8");

        @Override
        public boolean match(ResponseData responseData) {
            if (responseData == null) {
                return false;
            }

            // Check URL condition
            String urlCondition = conditions.get("url");
            if (urlCondition != null && responseData.getUrl() != null) {
                if (!responseData.getUrl().matches(urlCondition)) {
                    return false;
                }

     *
     * @param url The URL to search for.
     * @param hasData Whether to include data (currently not used in this implementation).
     * @return The list of access results.
     */
    @Override
    public List<OpenSearchAccessResult> getAccessResultList(final String url, final boolean hasData) {
        return getList(OpenSearchAccessResult.class, builder -> builder.setQuery(QueryBuilders.termQuery(URL, url)));
    }