docs: void addSubsystem(final OperationTransformerRegistry registry, final String name, final ModelVersion version) {
          final OperationTransformerRegistry profile = registry.getChild(PathAddress.pathAddress(PROFILE));
          final OperationTransformerRegistry server = registry.getChild(PathAddress.pathAddress(HOST, SERVER));
          final PathAddress address = PathAddress.pathAddress(PathElement.pathElement(ModelDescriptionConstants.SUBSYSTEM, name));
          subsystem.mergeSubtree(profile, Collections.singletonMap(address, version));
          if(server != null) {
              subsystem.mergeSubtree(server, Collections.singletonMap(address, version));
          }
      }