a bunch of new features in the Spring Web integration area
many enhancements, mainly aiming at improving performances
a lot of component upgrades, to pull in the latest / greatest available dependencies
some important bug fixes (including one for a potential memory leak in the Reactor Netty client integration)
In addition to that, RESTEasy 4.4.0.Final is the first version relying directly or indirectly on Jakarta EE API artifacts. We've been replacing all JavaEE API dependencies with the corresponding Jakarta EE 8 ones, while moving to new major versions of JBoss spec API artifacts (now forked from Jakarta EE APIs). This basically followed the same approach we used in WildFly (read more from Brian here, if interested).
The 4.4.0.Final release artifacts are available on Maven Central and JBoss Nexus repositories as usual and the distribution can also be downloaded at https://resteasy.github.io/.