May 27, 2022 Product Announcement Developers Urban Malc
KumuluzEE Java EE Microservices

KumuluzEE 4.0.0 released, with Java 17 LTS support, Jetty 10 and more!

We are happy to announce the next major release of KumuluzEE 4.0.0. This release includes a major Jetty upgrade, support for the latest released versions of Java, including the Java 17 LTS version and the use of JakartaEE 8 artifacts replacing the JavaEE 8 artifacts.

One of the major changes of this release is definitely the added support for the Java version 17. Java 17 is the latest LTS version, which are the most suitable versions for production use. Compared to the previous LST version (Java 11), Java 17 brings exciting new features such as records, text blocks, enhanced switch expressions, pattern matching of the instanceof operator, teeing collector for the Stream API and more.

Another exciting change in the new release of KumuluzEE is the transition from Jetty 9 to Jetty 10. The updated version of Jetty brings many important bugfixes and improvements. The Servlet API 4.0 is now fully implemented allowing better HTTP/2 support within internal components and general Servlet 4.0 usage according to the specification. The WebSocket implementation has been refactored, also allowing HTTP/2 usage. The Jetty HTTP client (used by internal components and our extensions, e.g. JAX-RS HTTP client, kumuluzee-rest-client’s backing HTTP client) has also been improved, with the major feature being the support for dynamic protocol upgrade to HTTP/2.

Another change in relation to Java versions is the end of support for the Java 1.8 runtime. The support for Java 1.8 was dropped in Jetty 10 and in turn we are also dropping support in KumuluzEE 4. If you are still running on Java 1.8, this is the perfect opportunity to upgrade, as the newer Java versions bring many exciting features.

Another transition we have made (also related to the Jetty 10 upgrade) is the transition from JavaEE 8 to JakartaEE 8 artifacts. This transition should not affect the actual code, only the locations and names of Maven artifacts. If you are referencing any JavaEE artifacts in your code, make sure to update the references there too.

The full list of breaking changes in this release:

  • KumuluzEE no longer supports Java 1.8 runtime, since the support for Java 1.8 has been dropped in Jetty 10.
  • Replaced JavaEE 8 artifacts with the JakartaEE 8 artifacts. If you are using JavaEE artifacts in your code, you should be able to find equivalent artifacts in the JakartaEE namespace.
  • Removed excludedAgentPatterns from gzip configuration since it was removed from Jetty.

See the full changelog below.


  • Upgraded from Jetty 9 to Jetty 10
  • Added support for Java 16, 17 and 18 and dropped support for Java 1.8
  • Use JakartaEE artifacts instead of JavaEE


  • Upped dependency versions
  • Removed excludedAgentPatterns from gzip configuration since it was removed from Jetty


  • Updated jar loading to add support for multi-release jars when running in UberJar
  • Added missing spaces in dependency validation log messages
  • More robust exception handling when loading configuration file
  • Updated JAX-WS annotation processor in order to support some edge cases

Check out the release on GitHub: KumuluzEE v4.0.0

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