* @param fields the fields to include in the response (null for all fields)
     * @return a list of child documents
     */
    public List<Map<String, Object>> getChildDocumentList(final SearchEngineClient searchEngineClient, final String id,
            final String[] fields) {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();

        final IndexingHelper indexingHelper = ComponentUtil.getIndexingHelper();
        final List<Map<String, Object>> docList =
                indexingHelper.getChildDocumentList(searchEngineClient, id, new String[] { fessConfig.getIndexFieldUrl() });
        if (docList.isEmpty()) {
            return null;
        }
        if (logger.isDebugEnabled()) {

                return docList;
            }
        };
        ComponentUtil.register(client, "searchEngineClient");

        final List<Map<String, Object>> documents = indexingHelper.getChildDocumentList(client, "001", new String[] { "title", "content" });
        assertEquals("fess.update", resultMap.get("index"));
        assertEquals(