private static void addFormatSet(SolrInputDocument doc, Collection<DcsFormat> set) {
    if (set == null || set.size() == 0) {
      return;
    }

    for (DcsFormat fmt : set) {
      setadd(doc, FormatField.NAME, fmt.getName());
      setadd(doc, FormatField.FORMAT, fmt.getFormat());
      setadd(doc, FormatField.SCHEMA, fmt.getSchemeUri());
      setadd(doc, FormatField.VERSION, fmt.getVersion());
    }
  }