final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final String updateAlias = fessConfig.getIndexDocumentUpdateIndex();
        final String searchAlias = fessConfig.getIndexDocumentSearchIndex();
        final GetIndexResponse response1 =
                client.admin().indices().prepareGetIndex().addIndices(updateAlias).execute().actionGet(fessConfig.getIndexIndicesTimeout());

     * The value is, e.g. fess.search <br>
     * comment: Index name for search documents.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getIndexDocumentSearchIndex();

    /**
     * Get the value for the key 'index.document.update.index'. <br>
     * The value is, e.g. fess.update <br>
     * comment: Index name for update documents.