Access to Continuation.yield and ContinuationScope

[Raul Raja Martinez]

Hello everyone,

First, thank you for LOOM and the extraordinary work done here. I'm excited
to see this coming to a final release.

I have been using LOOM builds up until recently, building abstractions
directly on top of what used to be `java.lang.Continuation` and the
`Continuation.yield` capabilities. I have noticed in the latest build these
became internal in the jdk.internal.vm package.

When I link against those I get errors like:

java.lang.IllegalAccessError: superclass access check failed: class
fx.Continuation$package$$anon$1 (in unnamed module @0x1f75bcda) cannot
access class jdk.internal.vm.ContinuationScope (in module java.base)
because module java.base does not export jdk.internal.vm to unnamed module
@0x1f75bcda

I wondered if there is a way to create and use Continuation.yield in this
latest build, and if not, how would I go about implementing a use case like
this currently expressed in Scala.

https://gist.github.com/raulraja/5bd7ffaf4f9fc44bf99fefc14a5e640e

Thank you!

Raul.