IIOPSubsystemAdd processes a non-existent 'configuration' model node

https://github.com/wildfly/wildfly/blob/master/iiop-openjdk/src/main/java/org/wildfly/iiop/openjdk/IIOPSubsystemAdd.java#L284

This code processes a 'configuration' attribute in the subsystem's root resource, but there is no such attribute, nor is there any child resource with that name.

JacORBSubsystemAdd extends IIOPSubsystemAdd, but the Jacorb subsystem doesn't have such an attribute or child either.