It seems JEE 8 servers (compliant with JAX-RS 2.1 API) conflict with deployment of resteasy-jaxrs.version 3.x (which is JAX-RS 2.0 API)
and JEE 7 servers (compliant with JAX-RS 2.0 API) conflict with deployment of resteasy-jaxrs.version 4.x (which is JAX-RS 2.1 API).
So by now there is no easy way to package a war file with resteasy included, that will run on both JEE 7 and 8.
I've successfully tested
<resteasy-jaxrs.version>4.0.0.Beta1</resteasy-jaxrs.version> on glassfish 5,
<resteasy-jaxrs.version>3.0.17.Final</resteasy-jaxrs.version> on glassfish 4,
<resteasy-jaxrs.version>3.1.4.Final</resteasy-jaxrs.version> on glassfish 4.
Note: transitioning resteasy-jaxrs from 3.0.x to any higher version involves removal of deprecated classes in
org.jboss.resteasy.client.*, which we are using it in core/viewer-resfulobjects-applib.