UserPrincipal, removed Apache CollectionUtils since we only had one use of one method
SecurityConfig, now uses a Bean to define the API security.
Created RestTemplateConfig, presently used only in ToBeReviewedCheckerServiceImpl
ToBeReviewedCheckerServiceImpl, removed restTemplate generator, as that is now done by RestTemplateConfig
To the tests, added @Import(SecurityConfig.class) so that it would load the security configuration before attempting a test API call, so that the call would be authorized as expected (or not).
pom.xml, updated versions of various dependencies to their most recent, and hopefully Java-22-compatible versions.