public List<String> getPermittedSubclasses() {
    StructPermittedSubclassesAttribute permittedSubClassAttr = getAttribute(StructGeneralAttribute.ATTRIBUTE_PERMITTED_SUBCLASSES);
    if (permittedSubClassAttr == null) return null;
    return permittedSubClassAttr.getClasses();
  }
public List<String> getPermittedSubclasses()