DelegatingSecurityContextExecutorService cannot be extended

Summary

I would like to use a PriorityBlockingQueue but also need access to the security context. The current implementation will not allow me to wrap the callable/runnable in a class that can implement comparable OR use a comparator that can see the wrapped class and make a sorting decision.

The wrapper is static and all classes and methods are marked final. I would like to be able to extend the class(es) that implement this delegate pattern to introduce a custom wrapper that can be sorted.

Start with DelegatingSecurityContextExecutorService and the related delegate-pattern classes described in the issue; inspect how their static wrappers and final classes or methods prevent extension. The work is done when a custom wrapper can be introduced for sorting in a PriorityBlockingQueue while preserving access to the security context, with tests covering that use case.