BoundedQueueThreadPoolService provides Executor instead of ExecutorService

Currently, there is no thread service that provides a j.u.c.ExecutorService using a bounded queue thread pool.
The existing BoundedQueueThreadPoolService only provides a j.u.c.Executor, instead of the far more useful j.u.c.ExecutorService. The exposed j.u.c.Executor cannot even be cast to an j.u.c.ExecutorService, since the underlying QueueExecutor is wrapped by a decorator that does not implement j.u.c.ExecutorService.