final List<String> docList = new ArrayList<>();

        indexingHelper.deleteDocumentsByDocId(client, docList);
        assertEquals("fess.update", resultMap.get("index"));
        assertEquals(0, ((List<String>) resultMap.get("ids")).size());

        docList.add("001");
        indexingHelper.deleteDocumentsByDocId(client, docList);
        assertEquals("fess.update", resultMap.get("index"));

     * @param searchEngineClient the search engine client to use for deletion
     * @param docIdList the list of document IDs to delete
     * @return the number of documents that were deleted
     */
    public long deleteDocumentsByDocId(final SearchEngineClient searchEngineClient, final List<String> docIdList) {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();