docs: @Override
      public  String appendRemoteFileExtension(final String filepath, final String fileext) {
          if (null == fileext) {
              return filepath;
          }
          String result = filepath;
          String ext = fileext;
          if (!ext.startsWith(".")) {
              ext = "." + fileext;
          }
          result += (filepath.endsWith(ext) ? "" : ext);
          return result;
      }