After starting the application use http://localhost:3000/swagger-ui/index.html to test its features.
Set and export the Spring Profiles environment variable before runnig the application (or set it in the run configuration in an IDE) so the in-memory h2 test database is used, when running the application locally for testing:
SPRING_PROFILES_ACTIVE=memdb
Tip: Run mvn install first, so the openapi maven plugin will generate the necessary API source files.