This is a minimal demo of using jpackage.
To configure it, create a file gradle.properties with two entries:
org.gradle.java.home=/path/to/jdk-11 jpackage.home=/path/to/jdk-13-with-jpackage
The idea is to build everything with JDK 11, and then use the early access jpackage just for packaging.
Then build:
./gradlew build
Then run:
build/app-image/demo/demo