Github user Jezza commented on the issue:
https://github.com/apache/wicket/pull/297
I actually just that this fixes a bug in the original.
You can't nest LLPs.
If you have a panel, it loads and builds the content, that's fine.
But if it contains another LLP then the visit will attempt to load that one
as well.
Which _could_ be fine, but the problem is is when the LLP tries to replace
the panel.
Because the nested panel's onBeforeRender hasn't fired yet, the loading
component was never added.
This solves that by just inserting the loading component immediately.
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