Upgrade to Spring Boot 3.1.x release train and update deprecated Spring Security code.

Bump other dependencies where needed.

Use Lombok for logging/domain objects - kept kicking this down the road for last 10 years... time to do it!

Cleanup entire codebase: minor Sonar issues, Javadocs, and typos.

Gradle 8.

Remove the legacy test adapter... and as much Powermock as possible - proving a nightmare since JDK 17.