static void register(BeanDefinitionRegistry registry) {
      if (!registry.containsBeanDefinition(BEAN_NAME)) {
        RootBeanDefinition definition = new RootBeanDefinition(SpyPostProcessor.class);
        definition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
        ConstructorArgumentValues constructorArguments = definition.getConstructorArgumentValues();
        constructorArguments.addIndexedArgumentValue(0, new RuntimeBeanReference(SpockMockPostprocessor.BEAN_NAME));
        registry.registerBeanDefinition(BEAN_NAME, definition);
      }
    }
{@link BeanPostProcessor} to handle {@link SpringSpy} definitions. Registered as a
separate processor so that it can be ordered above AOP post processors.
spock-spring/src/main/java/org/spockframework/spring/mock/SpockMockPostprocessor.java