Plugin is a Maven 2.x plugin, which will be not supported in Maven 4.x

Recent versions of Maven validate used Plugins and warn if a plugin might not work in Maven 4.x

This plugin is failing the validation:

```
[WARNING]  * org.assertj:assertj-assertions-generator-maven-plugin:2.2.0
[WARNING]   Plugin EXTERNAL issue(s):
[WARNING]    * Plugin is a Maven 2.x plugin, which will be not supported in Maven 4.x

```