ComponentUtil.getFessConfig().getApiJsonResponseHeaderList().forEach(e -> response.setHeader(e.getFirst(), e.getSecond()));
    }

    /**
     * Writes a JSON response.
     * @param status The status code.
     * @param t The throwable.
     */
    protected void writeJsonResponse(final int status, final Throwable t) {

        if (client == null) {
            throw new FessSystemException("No CrawlerClient: " + configId + ", url: " + url);
        }
        return writeContent(configId, url, client);
    }

    /**
     * Writes content from a crawler client to a stream response.
     *
     * @param configId the configuration ID
     * @param url the document URL
     * @param client the crawler client