The javax.xml.ws.spi.Provider resolution is based on the ServiceLoader.load(Provider.class) internals. That makes it JVM specific due to the different implementation of collections used to store the found resources.
This is critical as the jbossws-cxf client Provider impl is responsible for setting the proper thread Bus, ensuring proper deployment isolation.

We need to prevent potential issues (especially with IBM JDK) by avoiding duplicates of META-INF/services/javax.xml.ws.spi.Provider (Apache CXF one vs JBossWS-CXF one).