Class initialization deadlock in TypeDef

[jek6094]

If you build protocols from more than one thread at the same time, there is a risk of running into class initialization deadlocks in TypeDef. At this point there is no easy way to avoid this, so it needs fixing. I have attached a snippet from a thread dump of an occurrence of this issue. (all other threads have been omitted for the sake of simplicity)
clinit-deadlock.txt