[MPLUGIN-534] Cleanup master branch to only support building Maven 4 plugins

[jira-importer]

Konrad Windszus opened MPLUGIN-534 and commented

Currently in master there is still a lot of code only relevant for Maven 3 plugins. This needs cleanup to only support Maven 4. Maven 3 plugins must not be supported with master (4.x versions).

---

Issue Links:

• MPLUGIN-523 Split Maven3 and Maven4 support
  ("is caused by")