I converted your app to MVCI

[PerryCameron]

I came across this method of writing JavaFX
https://www.pragmaticcoding.ca/javafx/mvci/
I decided the best way to learn the MVCI method was to convert a simple JavaFX app into that framework. I choose your app because it was a perfect candidate. With some feedback from the author of the aforementioned blog. I came up with this.
https://github.com/PerryCameron/maven-jpackage-template

I didn't do a pull request, because your code is probably more appropriate for your use case here. I just thought you might find this interesting.