Robert Marcano thanks for the insight!

when initializing the CDI runtime. It would be helpful if the default Weld SE configuration could detect the security manager is active and choose another thread pool type.

Good idea. We should probably also log INFO when we switch this, just to let users know. And probably a WARN if user tries to manually enforce FJP through properties when running SM.
If you feel like it, please send a PR. Else we'll get to that, eventually