Currently if you have
jboss-negotiation-spnego-3.0.4.Final and jboss-negotiation-extras-3.0.4.Final.jar
on your module path, jvm complains as both jars export package org.jboss.security.negotiation.spnego
which violates the modules contract where only one module (jar) can provide single package.

example error that jvm prints

Error: Modules jboss.negotiation.extras and jboss.negotiation.spnego export package org.jboss.security.negotiation.spnego to module wildfly.clustering.common