code: protected void checkGridFTPSupport()
          throws IOException,
                 ServerException {
          FeatureList fl = getFeatureList();
          if (
              !(fl.contains(FeatureList.PARALLEL)
                && fl.contains(FeatureList.ESTO)
                && fl.contains(FeatureList.ERET)
                && fl.contains(FeatureList.SIZE))
              ) {
              throw new ServerException(ServerException.UNSUPPORTED_FEATURE);
          }
      }
docs: assure that the server supports extended transfer features;
  throw exception if not