public Object getData(final AccessResultData<?> accessResultData) {
        // check transformer name
        if (!getName().equals(accessResultData.getTransformerName())) {
            throw new CrawlerSystemException(
                    "Transformer is invalid. Use " + accessResultData.getTransformerName() + ". This transformer is " + getName() + ".");
        }

        final byte[] data = accessResultData.getData();
        if (data == null) {