There are a set of "Bootstap" classes which when present in the web.xml file require
jaxrs (i.e. resteasy) components to be configured using Resteasy Configuration Switches.
(see https://docs.jboss.org/resteasy/docs/3.0.4.Final/userguide/html/Installation_Configuration.html#d4e125 )
Adding the following switch to the web.xml should solve the issue.

2 resteasy config switches need to be added dynamically when a jaxrs Application subclass is found in the web.xml file.

This addresses the issue flagged in https://issues.jboss.org/browse/JBEAP-8064