In the xxx-fixture project, reference the JPA services implementations module in the <dependencies> section:

<dependencies>
  ...
  <dependency>
    <groupId>${project.groupId}</groupId>
    <artifactId>xxx-jpa-service</artifactId>
  </dependency>
  ...
</dependencies>

TODO: I can't recall why this is needed; hence the lack of commentary here. There's probably a good reason, but it escapes me...