private static DcsCollectionRef getCollectionRef(SolrDocument doc, SolrName field) {
    DcsCollectionRef ref = new DcsCollectionRef();

    String s = get(doc, field);

    if (s != null) {
      ref.setRef(s);
    }

    return ref;
  }
  private static Set<DcsCollectionRef> getCollectionRefSet(SolrDocument doc, SolrName field) {
    Set<DcsCollectionRef> set = new HashSet<DcsCollectionRef>();

    for (String s : setgetAll(doc, field)) {
      DcsCollectionRef ref = new DcsCollectionRef();

      if (s != null) {
        ref.setRef(s);
      }

      set.add(ref);
    }

    return set;
  }