I couldn't find very many sample programs that were both simple enough and complicated enough for my purposes in learning Spring HATEOAS along with Spock Tests. I finally came across [Taimoor Choudhary|https://github.com/TaimoorChoudhary] and his [spring-HATEOAS example|https://github.com/TaimoorChoudhary/spring-HATEOAS].
I have modified it past the point of compatibility with his original code. I removed usage of Mapper and Lombok, and switched the build method to Gradle from Maven.