FWIW in WildFly 9 Jackson 2 will be the default, [WFLY-3200] Support Jackson 2 out of the box - JBoss Issue Tracker.
To get it to work in WildFly 8 or JBoss EAP/JBoss AS 7.1.1.Final you need to add a jboss-deployment-structure.xml with the following content.
<jboss-deployment-structure> <deployment> <exclusions> <module name="org.jboss.resteasy.resteasy-jackson-provider"/> </exclusions> <dependencies> <module name="org.jboss.resteasy.resteasy-jackson2-provider" services="import"/> </dependencies> </deployment> </jboss-deployment-structure>
There is more information in the documentation Chapter 21. JSON Support via Jackson.
James R. Perkins
Bit of an update.
as of latest nightly builds and 8.1.0.CR2 that is going to be released shortly, Jackson2 became default JSON provider in WildFly.
In short, workarounds as described above have become obsolete.