final Map<String, AccessResultImpl<Long>> arMap = dataHelper.getAccessResultMap(accessResult.getSessionId());
            if (arMap.containsKey(accessResult.getUrl())) {
                throw new CrawlerSystemException(accessResult.getUrl() + " already exists.");
            }
            arMap.put(accessResult.getUrl(), accessResult);
        }

    }

    /**

        Map<String, AccessResultImpl<Long>> arMap = sessionMap.get(sessionId);
        if (arMap == null) {
            arMap = new HashMap<>();
            sessionMap.put(sessionId, arMap);
        }
        return arMap;
    }

    /**
     * Deletes the access result map for the specified session ID.
     * @param sessionId the session ID

        final Queue<UrlQueueImpl<Long>> urlQueueList = dataHelper.getUrlQueueList(sessionId);
        final Map<String, AccessResultImpl<Long>> arMap = dataHelper.getAccessResultMap(previousSessionId);
        for (final Map.Entry<String, AccessResultImpl<Long>> entry : arMap.entrySet()) {
            synchronized (urlQueueList) {
                final UrlQueueImpl<Long> urlQueue = new UrlQueueImpl<>();