JBossDeveloper

It's in the docs

You should have at least

• jaxrs-api.jar


• resteasy-jaxrs.jar


• jboss-seam-resteasy.jar

in the WEB-INF/lib for war deployment or in {ear.home}/lib dir if using ear deployment.

If it's any help, I hit the same problem, and you need

• resteasy-jackson-provider.jar

Along with the jars mentioned in the docs.

(I guess you can use other providers such a jettison)