WELD-56 has been resolved a while ago however the docs still say:
A future release of Weld will likely support a non-standard workaround for this limitation, using non-portable JVM APIs:
Sun, IcedTea, Mac: Unsafe.allocateInstance() (The most efficient)
IBM, JRockit: ReflectionFactory.newConstructorForSerialization()
But we didn't get around to implementing this yet.