private static Set<DcsResourceIdentifier> getResourceIdentifierSet(SolrDocument doc) {
    Set<DcsResourceIdentifier> idSet = new HashSet<DcsResourceIdentifier>();

    String[] authorities = setgetAll(doc, ResourceIdentifierField.AUTHORITY);
    String[] types = setgetAll(doc, ResourceIdentifierField.TYPE);
    String[] values = setgetAll(doc, ResourceIdentifierField.VALUE);

    for (int i = 0; i < values.length; i++) {

      DcsResourceIdentifier id = new DcsResourceIdentifier();

      id.setAuthorityId(authorities[i]);
      id.setTypeId(types[i]);
      id.setIdValue(values[i]);

      idSet.add(id);
    }

    return idSet;
  }