A beginner’s guide to the Jenesis build tool

Hi,

In my latest article, I’m going to show you how we can build the Hypersistence Utils project with Jenesis, a new Java build tool created by Rafael Winterhalter, who’s a Java Champion, author of Byte Buddy and a major contributor to Mockito.

If you haven’t heard of it yet, check out this introductory article first.

What is Jenesis

Jenesis is a build tool whose engine is just plain Java code that you can embed into your project in the build/jenesis folder. I first heard of Jenesis at JavaZone 2026 during this talk that Rafael Winterhalter gave about it:

Since I promised Rafael that I’d give it a try, this article will show you exactly how I added support for Jenesis in my Hypersistence Utils project, which has three Hibernate modules, and almost 1,000 integration tests that can run on PostgreSQL, MySQL, Oracle, and SQL Server, either locally or using Testcontainers. So, it’s not a trivial project to test a build tool.

One of the first things that you’ll discover is that there’s no external command to run the build, because Jenesis runs on your local Java 25 or newer:

For an existing project, Jenesis can read the pom.xml files, so I didn’t have to migrate from pom.xml to something else, as is the case with Gradle. In my case, this is very convenient as I can run both Maven and Jenesis side by side since both will build from the very same POMs.

For more details about how I used Jenesis to build Hypersistence Utils, check out this article.

Thank you for reading and have a wonderful week-end!