prerequisite tag reserved for maven-plugin projects
prerequisite tag reserved for maven-plugin projects

When building this project, a warning is issues at the beginning:
```log
[INFO] Scanning for projects...
[WARNING] The project org.threeten:threeten-extra:jar:1.3-SNAPSHOT uses prerequisites which is only intended for maven-plugin projects but not for non maven-plugin projects. For such purposes you should use the maven-enforcer-plugin. See https://maven.apache.org/enforcer/enforcer-rules/requireMavenVersion.html
```

The mentioned maven-enforcer-plugin achieves the same purpose, just for NON maven-plugin projects.

catull/threeten-extra,ThreeTen/threeten-extra