Commit ccd17d introduced a regression where a custom HTTP method
would no longer match for an empty @RequestMapping condition.
The previous behavior should now be restored. Effectively
RequestMethodRequestCondition as before will now match to any HTTP
method (even unknown/custom ones) if the methods condition is empty.
The only exception is HTTP OPTIONS for which we provide default
handling as a fallback (i.e. when not mapped explicitly).
Issue: SPR-13130
08eb623c41