ResponseData responseData = new ResponseData();
        Map<String, Object> dataMap = new HashMap<>();
        assertEquals("", documentHelper.getContent(null, responseData, null, dataMap));
        assertEquals("", documentHelper.getContent(null, responseData, "", dataMap));
        assertEquals("", documentHelper.getContent(null, responseData, " ", dataMap));

            }
            ResponseData responseData = new ResponseData();
            responseData.setCharSet("UTF-8");
            responseData.setContentLength(data.length());
            responseData.setExecutionTime(1000L);
            responseData.setHttpStatusCode(200);
            responseData.setLastModified(new Date());
            responseData.setMethod("GET");

        responseData.setExecutionTime(500L);
        assertEquals(500L, responseData.getExecutionTime());
    }

    @Test
    public void test_responseData_parentUrl() {
        final ResponseData responseData = new ResponseData();

        assertNull(responseData.getParentUrl());
        responseData.setParentUrl("http://example.com/parent");

     * Get the extractor.
     * @param responseData The response data.
     * @return The extractor.
     */
    protected abstract Extractor getExtractor(ResponseData responseData);

    @Override
    public ResultData transform(final ResponseData responseData) {
        if (responseData == null || !responseData.hasResponseBody()) {
            final String url = responseData != null ? responseData.getUrl() : "unknown";

     *
     * @param responseData the response data containing the document to extract
     * @return the extractor instance for processing the document
     * @throws FessSystemException if no suitable extractor can be found
     */
    @Override
    protected Extractor getExtractor(final ResponseData responseData) {

     *
     * @param responseData the response data from crawling
     * @param resultData the result data to store processed information
     */
    @Override
    protected void storeData(final ResponseData responseData, final ResultData resultData) {
        final DOMParser parser = getDomParser();
        try (final BufferedInputStream bis = new BufferedInputStream(responseData.getResponseBody())) {

     * Default implementation returns the target unchanged.
     *
     * @param target the result data to process
     * @param responseData the response data from crawling
     * @return the processed result data
     */
    public ResultData process(final ResultData target, final ResponseData responseData) {
        return target;
    }

    /**
     * Processes a document map for web/file crawling with access result.

                if (responseData == null) {
                    // head method
                    responseData = client.execute(RequestDataBuilder.newRequestData().head().url(url).build());
                    if (responseData == null) {
                        return true;
                    }
                }

                final int httpStatusCode = responseData.getHttpStatusCode();

        final ResponseData responseData = client.execute(RequestDataBuilder.newRequestData().get().url(url).build());
        if (responseData.getHttpStatusCode() == 404) {
            response.httpStatus(responseData.getHttpStatusCode());
            CloseableUtil.closeQuietly(responseData);
            return response;
        }
        writeFileName(response, responseData);

        try (final ResponseData responseData = client.execute(RequestDataBuilder.newRequestData().get().url(url).build())) {
            if (responseData.getRedirectLocation() != null) {
                final Set<RequestData> childUrlList = new HashSet<>();
                childUrlList.add(RequestDataBuilder.newRequestData().get().url(responseData.getRedirectLocation()).build());