class BeanHierarchy {

  Set<Class<? extends Bean>> subtypes(Class<?> type) {
    Node node = _nodes.get(type);
    if (node == null) {
      return Collections.emptySet();
    }
    Set<Class<? extends Bean>> types = Sets.newHashSet();
    addSubtypes(node, types);
    return types;
  }

    BeanHierarchy(Set<MetaBean> metaBeans);

}