You might have recently read about the very interesting new features being developed these days in RESTEasy... great, the time has come to deliver them in a couple of releases!
Last week, RESTEasy 3.6.0.Final and 4.0.0.Beta4 have been tagged, built and published; here is a list of the most relevant additions coming with them:
- client and server side reactive extensions 
- parameter annotations with default names 
- JettyClientEngine to use jetty-client with JAX-RS Client 
- SPI to modify resource metadata 
Moreover, 4.0.0.Beta4, also feature the first part of the changes for the tracing system  and asynchronous container filters  support.
Both releases are available on the usual Maven repository, feel free to try them out!
3.6.0.Final is also being pulled into WildFly master, targetting inclusion in WildFly 14 release.
 Asynchronous, reactive, rxjava and beyond!
 Chapter 39. Reactive programming support
 New DRY-er annotations for parameters
 Chapter 13. Improved @…Param annotations
 Chapter 50. RESTEasy Client API
 Chapter 18. Resources metadata configuration
 A brief introduction to the RESTEasy Tracing Feature
 New: Asynchronous container filters