Spring AOT-generated code no longer sets bean class for beans created from a @Bean method

When using spring native with AOT processing, source generation for bean with version 6.0.10 produces:

  public static BeanDefinition getMyBeanBeanDefinition() {
    Class<?> beanType = MyBean.class;
    RootBeanDefinition beanDefinition = new RootBeanDefinition(beanType);
    beanDefinition.setInstanceSupplier(getMyBeanInstanceSupplier());
    return beanDefinition;
  }

Using version 6.0.11 produces:

  public static BeanDefinition getMyBeanBeanDefinition() {
    RootBeanDefinition beanDefinition = new RootBeanDefinition();
    beanDefinition.setTargetType(MyBean.class);
    beanDefinition.setInstanceSupplier(getMyBeanInstanceSupplier());
    return beanDefinition;
  }

Then, when entering a postProcessAfterInitialization method of a BeanFactoryPostProcessor, the bean definition seems uncomplete using 6.0.11. Did not figured out why yet, but stuff working with aot and native for month stops working when using 6.0.11 of spring-boot.

I used generated sources from an AOT processing performed with 6.0.10 to produce an artifact with version 6.0.11, These 2 lines make the behaviour change.

Comment From: snicoll

Thanks for the report. I am afraid we will need a bit more detail, as the two definitions above should be identical.

Please share a small sample that we can use to reproduce the problem. You can share it with us by pushing it to a separate GitHub repository.

Comment From: itineric

The repository: https://github.com/itineric/spring-framework-issue-31242

Started with the Hello world to reproduce it easilly.

Expected output is:

INFO 1609667 --- [           main] c.itineric.MyBeanFactoryPostProcessor    : name: myBean
INFO 1609667 --- [           main] c.itineric.MyBeanFactoryPostProcessor    : getBeanClassName: com.itineric.MyBean

And it is working with following dependency (and previous versions):

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
  <version>3.1.1</version>
</dependency>

When switching to version 3.1.2

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
  <version>3.1.2</version>
</dependency>

output changes to (bean class name is now null)

INFO 1611385 --- [           main] c.itineric.MyBeanFactoryPostProcessor    : name: myBean
INFO 1611385 --- [           main] c.itineric.MyBeanFactoryPostProcessor    : getBeanClassName: null

More precisely, the fault is with the spring-boot version that switches from 6.0.10 to 6.0.11.

Comment From: snicoll

Thanks for the feedback. I've edited your comment to remove what you've already stated in the original description.

We've now established that a BeanFactoryPostProcessor is expecting beanClassName to be set and that is not correct. If you had a bean with a generic type with 3.1.1 the generated code would only set the resolvable type, not the bean class so you would end up in the same situation. In general, there are other situations outside of AOT where this field might not have been set so expecting all bean definitions to have it is not correct I am afraid.

If you need to access the beanClass, beanDefinition.getResolvableType().toClass() would give you that information.

Can you share a bit more about the actual BeanFactoryPostProcessor? Is it your own code or a third party? Why does it need the class name?

@jhoeller wondering if we could change things a bit in RBD to set the beanClassName as well if it is null or is it weird?

Comment From: itineric

The first BeanFactoryPostProcessor I am getting troubles with is: https://github.com/resteasy/resteasy-spring/blob/main/resteasy-spring/src/main/java/org/jboss/resteasy/plugins/spring/SpringBeanProcessor.java

Why it does not work anymore with null? See https://github.com/resteasy/resteasy-spring/blob/main/resteasy-spring/src/main/java/org/jboss/resteasy/plugins/spring/SpringBeanProcessor.java#L278 and https://github.com/resteasy/resteasy-spring/blob/main/resteasy-spring/src/main/java/org/jboss/resteasy/plugins/spring/SpringBeanProcessor.java#L399

I may have others but started the digging with this one.

Comment From: itineric

Something odd related to this: the AOT generated code is not the same when the @Bean is retrieved from a method instance a @Configuration class and when it is a @Component.

With @Bean on a method myBean():

public static BeanDefinition getMyBeanBeanDefinition() {
    RootBeanDefinition beanDefinition = new RootBeanDefinition();
    beanDefinition.setTargetType(MyBean.class);
    beanDefinition.setInstanceSupplier(getMyBeanInstanceSupplier());
    return beanDefinition;
  }

With @Component on MyBeanclass:

public static BeanDefinition getMyBeanBeanDefinition() {
    RootBeanDefinition beanDefinition = new RootBeanDefinition(MyBean.class);
    beanDefinition.setInstanceSupplier(MyBean::new);
    return beanDefinition;
  }

Comment From: snicoll

Ouch, that's not right. I've created #31251

Comment From: snicoll

OK now that I've actually looked at the code, I can see what's happening. Regarding:

  public static BeanDefinition getMyBeanBeanDefinition() {
    RootBeanDefinition beanDefinition = new RootBeanDefinition();
    beanDefinition.setTargetType(MyBean.class);
    beanDefinition.setInstanceSupplier(getMyBeanInstanceSupplier());
    return beanDefinition;
  }

This is generated if the bean definition we're inspecting actually does not have a beanClass. So this new RootBeanDefinition() means that MyBean.class has no beanClass associated with it. Ironically, we were setting it previously and that was working for you.

I think the thing that's checking for the beanClass might be missing a case. I'll have a look.

Comment From: snicoll

It isn't, really. beans produced by a @Bean method don't have a bean class. They don't have a beanClassName either. They do have a getFactoryBeanName() however but that is no longer relevant once AOT has processed the bean as it is no longer produced that way.

We do restore the factoryMethodToIntrospect though, as we need to be able to collect the annotations on the original factory method if necessary. But not the metadata about the factoryMethodBeanName as we don't need it.

I can't say enough about RESTEasy but I think the code there is a bit fragile and should probably be updated.