I’ve just published my article Using the Java Packager with JDK 11 on Medium. You can read all about how to package a JDK 11 application into a bundle that can be installed on Mac, Windows or Linux. A worked example is given based on the Open Source Santulator project.
Update: jpackage is now Production-Ready
As of JDK 16, jpackage is now production-ready. I’ve written an updated article, Installable Java Apps with jpackage and I would recommend that now, rather than the orginal article.