I have since discovered that there is an open jira to make undertow OSGi compliant and the devs seem game. I think I'll recommend that they just just set the classloader they want to be the tccl, call serviceloader in the way I'd like and then restore the tccl.
I do however think it's a nice enhancement to spi-fly, and I haven't done anything with asm in ages so I will probably have a crack at a patch as a second order concern (and a handy backup if the direct route fails). Thanks, Ben
