Major Description
I have a page that adds a panel which has a markup header contribution (wicket:head). The page has no head or body tag. In wicket 1.4, this logs a conspicuous error message, but in wicket 6 it ignores it silently.
I see that validateHeaders still tries to render the header and check if there was anything added, but the problem is that the header does not get rendered into the response object it's checking.