Should @Configuration mark @Inject fields and setters as satisfied (injected)? [SPR-14180]

Christian Hersevoort opened SPR-14180 and commented

Somewhat related to my other issue: #18750 (It's a different way to solve the same problem)

The case is as follows:

Beans:

• MyParentBean
• MyChildBeanA implements MyChildBean
• MyChildBeanB implements MyChildBean

@Configuration
public class MyBeanConfiguration
{
	@Bean
	public MyParentBean myParentBean(MyChildBeanA childBeanA)
	{
		MyParentBean myParentBean = new MyParentBean();
		myParentBean.setMyChild(childBeanA);
		return myParentBean;
	}
}

@Component
public class MyParentBean
{
	private MyChildBean myChild;

	@Inject
	public void setMyChild(MyChildBean myChild)
	{
		this.myChild = myChild;
	}
}

I expect the MyParentBean.myChild field to only be Injected by the @Configuration, and not by both ConfigurationClassPostProcessor and the AutowiredAnnotationBeanPostProcessor.

Expected:

1. ConfigurationClassPostProcessor calls MyBeanConfiguration
2. MyParentBean is created and field/property myChild is set.
3. myChild is marked as satisfied(Injected)

What happens:

1. ConfigurationClassPostProcessor calls MyBeanConfiguration
2. MyParentBean is created and field/property myChild is set.
3. AutowiredAnnotationBeanPostProcessor tries to Inject myChild again, but fails and throws a NoUniqueBeanDefinitionException

Changing between field and property injection doesn't help either e.g:

@Component
public class MyParentBean
{
	@Inject
	private MyChildBean myChild;
}

Changing @Bean to @Bean(autowire = Autowire.NO) doesn't help either, e.g:

@Configuration
public class MyBeanConfiguration
{
	@Bean(autowire = Autowire.NO)
	public MyParentBean myParentBean(MyChildBeanA childBeanA)
	{
		MyParentBean myParentBean = new MyParentBean();
		myParentBean.setMyChild(childBeanA);
		return myParentBean;
	}
}

Is this expected behavior? I expect org.springframework.beans.factory.annotation.InjectionMetadata.InjectedElement#checkPropertySkipping to be true and skip injection.

If this is expected behavior: is there a way to prevent @Bean to be injected again by the AutowiredAnnotationBeanPostProcessor?

Issue Links:

• #18750 Inconsistency between property Injection and setter Injection causes NoUniqueBeanDefinitionException
• #18854 Clarify @Bean(autowire=NO)

Start by tracing ConfigurationClassPostProcessor and AutowiredAnnotationBeanPostProcessor for the MyParentBean example, then inspect InjectionMetadata.InjectedElement#checkPropertySkipping. Determine whether configuration-time setter or field injection should be recognized as already satisfied, and define completion as preventing the duplicate injection and resulting NoUniqueBeanDefinitionException.