I feel like they used to work but there were gotchas. For example the JVM loads up some types before the LTW infrastructure can even get involved and those can't be woven. I don't actually recall if we have testcases for this but I wouldn't be surprised if they weren't there. I guess you have tried them and they don't work - I wonder if you were test weaving something that would be loaded early? It would be interesting to attempt it with a -verbose:class and verify not attempting to weave things loaded before the 'LTW is active' type messages come out. Will it work with modules in recent Javas? That seems unlikely.
But it could be the kind of classloaders in use in regular Java now don't allow weaver attachment, I honestly haven't kept up to speed on that - and maybe that prevents them working at all. A run of LTW with the debug option on for the weaver should show the types the weaver is being exposed to. If those are java/javax then they should be weavable.
cheers,
Andy
