It is not necessary to register to use build scans. The only thing you needed to do, is add that license agreement acceptance block that I pasted in the steps. Thanks anyway for trying though, @Graou74 
All is not lost however 
How about removing the --scan argument then? It’s important that you also do your „remove the com.lingocoder plugin from the Gradle cache“ step this time.
The --debug argument should result in there being some important debug entries from mrJar printed to the console. Those will provide super valuable insight into what specificallly might need to be refactored in mrJar.
The --stacktrace argument will result in the exception that’s produced by the :test run being dumped to Eclipse’s Error Log.
Sharing both of those via a simple .txt file would be awesome. Please, @Graou74? TIA.