if (ResourceUtil.isExist(dataPath)) {
                    insertBulkData(fessConfig, indexName, dataPath);
                }
                split(fessConfig.getAppExtensionNames(), ",").of(stream -> stream.filter(StringUtil::isNotBlank).forEach(name -> {
                    final String bulkPath =

     * The value is, e.g.  <br>
     * comment: Extension names for application customization.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getAppExtensionNames();

    /**
     * Get the value for the key 'app.extension.names' as {@link Integer}. <br>
     * The value is, e.g.  <br>
     * comment: Extension names for application customization.