HttpClient httpClient = HttpClientBuilder.create()
            .setDefaultRequestConfig(requestBuilder.build()).build();

        Queue<String> queue = getUrls();

        String url;
        int count = 0;
        while((url = queue.poll()) != null && count < max) {

            try {
                Logger.info("crawling: " + url);

  }

  /** Returns the URLs in the class path. */
  static URL[] getClassPathUrls() {
    return ClassPathUtil.class.getClassLoader() instanceof URLClassLoader
        ? ((URLClassLoader) ClassPathUtil.class.getClassLoader()).getURLs()
        : parseJavaClassPath();
  }

  }

  /** Returns the URLs in the class path. */
  static URL[] getClassPathUrls() {
    return ClassPathUtil.class.getClassLoader() instanceof URLClassLoader
        ? ((URLClassLoader) ClassPathUtil.class.getClassLoader()).getURLs()
        : parseJavaClassPath();
  }

  private URL[] getClassPathUrls() {
    ClassLoader classLoader = getClass().getClassLoader();
    return classLoader instanceof URLClassLoader
        ? ((URLClassLoader) classLoader).getURLs()
        : parseJavaClassPath().toArray(new URL[0]);
  }

  /**
   * Returns the URLs in the class path specified by the {@code java.class.path} {@linkplain
   * System#getProperty system property}.
   */

        final Set<String> urlSet = new HashSet<>();
        final List<UrlQueue<?>> childList = childUrlList.stream().filter(d -> StringUtil.isNotBlank(d.getUrl())
                && urlSet.add(d.getUrl() + "\n" + d.getMetaData()) && crawlerContext.getUrlFilter().match(d.getUrl())).map(d -> {
                    final UrlQueue<?> uq = crawlerContainer.getComponent("urlQueue");
                    uq.setCreateTime(SystemUtil.currentTimeMillis());

            if (arMap.containsKey(accessResult.getUrl())) {
                throw new CrawlerSystemException(accessResult.getUrl() + " already exists.");
            }
            arMap.put(accessResult.getUrl(), accessResult);
        }

    }

    /*
     * (non-Javadoc)
     *

                assertTrue(urlQueue.getUrl() + "=>" + url1, urlQueue.getUrl().startsWith(url1));
            }
            while ((urlQueue = urlQueueService.poll(sessionId2)) != null) {
                assertTrue(urlQueue.getUrl() + "=>" + url2, urlQueue.getUrl().startsWith(url2));
            }

            dataService.iterate(sessionId1, accessResult -> assertTrue(accessResult.getUrl().startsWith(url1)));

                    }
                    break;
                default:
                    logger.error("Unknown thumbnail result: {} -> {}", thumbnailId, responseData.getUrl());
                    break;
                }
            } catch (final Throwable t) {
                logger.warn("Failed to create thumbnail: {} -> {} ({}:{})", thumbnailId, responseData.getUrl(),

    }

    @Override
    public ResponseData execute(final RequestData request) {
        return switch (request.getMethod()) {
        case GET -> doGet(request.getUrl());
        case HEAD -> doHead(request.getUrl());
        case POST -> doPost(request.getUrl());
        default -> throw new CrawlerSystemException(request.getMethod() + " method is not supported.");
        };
    }

     * {@link RemoteRepository#getUrl()} root.
     *
     * @throws RuntimeException If PUT fails for any reason.
     */
    void put(@Nonnull Path source, @Nonnull URI relativeTarget);

    /**
     * PUTs the source byte array to target URI. The target MUST BE relative from the
     * {@link RemoteRepository#getUrl()} root.
     *
     * @throws RuntimeException If PUT fails for any reason.