The bootstrap class loader has all permissions. There is no requirement for jaxws classes be loaded by null class loader. JDK-8038970 has prepared the jaxws implementation to be loaded by a non-null class loader.

JAX-WS classes be loaded by the extension class loader in JDK 9 will only grant the specified permissions and improve security.

This is important to allow EE upgrade/override this module with a new version.