ejb3/src/main/java/org/jboss/as/ejb3/deployment/processors/MessageDrivenComponentDescriptionFactory.java
private String getDefaultResourceAdapterName(final ServiceRegistry serviceRegistry) {
        if (appclient) {
            // we must report the MDB, but we can't use any MDB/JCA facilities
            return "n/a";
        }
        final ServiceController<DefaultResourceAdapterService> serviceController = (ServiceController<DefaultResourceAdapterService>) serviceRegistry.getRequiredService(DefaultResourceAdapterService.DEFAULT_RA_NAME_SERVICE_NAME);
        return serviceController.getValue().getDefaultResourceAdapterName();
    }
private String getDefaultResourceAdapterName(final ServiceRegistry serviceRegistry) {
        if (appclient) {
            // we must report the MDB, but we can't use any MDB/JCA facilities
            return "n/a";
        }
        final ServiceController<DefaultResourceAdapterService> serviceController = (ServiceController<DefaultResourceAdapterService>) serviceRegistry.getRequiredService(DefaultResourceAdapterService.DEFAULT_RA_NAME_SERVICE_NAME);
        return serviceController.getValue().getDefaultResourceAdapterName();
    }
Returns the name of the resource adapter which will be used as the default RA for MDBs (unless overridden by
the MDBs).

@param serviceRegistry
@return