Although elytron has module for JACC factory it is not used for JACC

A module can be specified and this is used to load the specified provider class and instantiate it, however this is separate to the one instantiated by PolicyConfigurationFactory.

Elytron does set a system property to ensure the configured class name is used but does not actually ensure the module is used for class loading.

At the same time it should be ensuring there is only a single instance of the class.

Finally we should verify the correct class has been loaded in case some race condition has caused premature initialisation - those can be difficult to debug.