@Override
  public void setAncestor(NodeDescriptor oldDescriptor) {
    super.setAncestor(oldDescriptor);
    final Boolean isPrimitive = ((FieldDescriptorImpl)oldDescriptor).myIsPrimitive;
    if (isPrimitive != null) { // was cached
      // do not loose cached info
      myIsPrimitive = isPrimitive;
    }
  }
@Override
  public void setAncestor(NodeDescriptor oldDescriptor)