sclass ConceptShadow {

  Map map;

  bool refsConvertedToIDs;

  *(Concept c) {

    map = conceptShadow_rawMap(c);

    MetaTransformer tf = metaTransformer_collectionAndMap();

    // dereference concept refs

    map = toSortedArrayBasedMap((Map) tf.transform(lambda1 derefRefOrNull, map);

  }

  synchronized selfType convertRefsToIDs() {

    if (refsConvertedToIDs) this;

    set refsConvertedToIDs;

    MetaTransformer tf = metaTransformer_collectionAndMap();

    map = toSortedArrayBasedMap(mapValues(map, o -> tf.transform(lambda1 conceptToIDObj_gen, o)));

    this;

  }

  toString { ret "ConceptShadow " + stringIf(refsConvertedToIDs, "[converted] ") + map; }

  O get(O key) { ret mapGet(map, key); }

  public bool equals(O o) {

    if (o cast ConceptShadow) {

      convertRefsToIDs();

      o.convertRefsToIDs();

      ret eq(map, o.map);

    }

    false;

  }

  long id() { ret toLong(get("id")); }

}