Demo interoperation with USubscription service

[gregmedd]

This can be written as an application that copies USubscription client behavior from the Java, Rust, or Python implementation to demo that it works. It can be written in terms of L2 API calls. The L3 API does not need to be written for this.

[gregmedd]

The original plan was to demo this today. However, I ended up out sick this week and unable to work on this. Some degree of interoperability was demoed using the TCK. We will need to determine if this task is still needed, or if it can be deferred until L3 APIs are completed.