Bug: The component(s) below failed to render.

[Vit Rozkovec]

Hi fellow wicketeers,

I've created an issue with what I believe is a bug in Wicket 8.11.0.
https://issues.apache.org/jira/browse/WICKET-6870

Is it some wrong (ab)use of the framework from my side? This code worked 
in wicket 8.10.0 and all previous versions.

Could you please have a look at it? It blocks me from upgrading to 8.11.0

Thank you very much!

Vit