SpringBoot Is @ConditionalOnBean affected by the Bean load order, rather than affecting the Bean load order, is it reasonable?

    @Bean
    @ConditionalOnBean(B.class)
    public A a() {
        return new A();
    }

    @Bean  
    //@ConditionalOnBean(A.class)
    public B b() {
        return new B();
    }

The above code, only bean type named B can be loaded, the following code, bean type name A and bean type named B both be load.

    @Bean
    //@ConditionalOnBean(B.class)
    public A a() {
        return new A();
    }

    @Bean  
    @ConditionalOnBean(A.class)
    public B b() {
        return new B();
    }

The writing order is different, and different effects are produced. Is it reasonable?

For the first demo code, should spring try to load B as much as possible when spring have scanned @ConditionalOnBean(B.class)?

Comment From: snicoll

The Javadoc of @ConditionalBean has a note describing how it should be used. You must make sure the bean that is a target of the condition has been loaded before the condition applies.

In the future, please ask questions on StackOverflow: as mentioned in the guidelines for contributing, we prefer to use GitHub issues only for bugs and enhancements.

Comment From: bjmi

I recently had the same issue after splitting a big configuration class into two smaller ones. Afterwards some beans weren't instantiated anymore that used @ConditionalOnBean. For me this is a bug too. Otherwise @ConditionalOnBean become useless and discouraged as the behaviour is unspecific. See also: #7815