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());

                throw new CrawlerSystemException("exception " + count);
            }

            final ResponseData responseData = new ResponseData();
            responseData.setUrl(request.getUrl());
            responseData.setMethod(request.getMethod().toString());
            return responseData;
        }

        /*
         * (non-Javadoc)
         *

        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.urlFilter.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)
     *

                && isValidCanonicalUrl(responseData.getUrl(), canonicalUrl)) {
            final Set<RequestData> childUrlSet = new HashSet<>();
            childUrlSet.add(RequestDataBuilder.newRequestData().get().url(canonicalUrl).build());
            logger.info("CANONICAL: {} -> {}", responseData.getUrl(), canonicalUrl);

                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)));

            logger.debug("Crawling Access Exception at {}", urlQueue.getUrl(), e);
        } else if (e.isInfoEnabled()) {
            logger.info(e.getMessage());
        } else if (e.isWarnEnabled()) {
            logger.warn("Crawling Access Exception at " + urlQueue.getUrl(), e);
        } else if (e.isErrorEnabled()) {
            logger.error("Crawling Access Exception at " + urlQueue.getUrl(), e);
        }
    }

                    }
                    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.");
        };
    }

        final String url = urlQueue.getUrl();
        if (StringUtil.isBlank(url)) {
            if (logger.isDebugEnabled()) {
                logger.debug("URL is a blank: {}", url);
            }
            return false;
        }

        // check it in queue
        for (final UrlQueue<Long> urlInQueue : urlQueueList) {
            if (url.equals(urlInQueue.getUrl())) {