Bean registration example

MyAutoConfiguration.java

class MyAutoConfiguration {
    @Bean
    public static BeanFactoryPostProcessor behandleserviceRegistrationBeanFactory() {
        return factory -> {
            if (!(factory instanceof BeanDefinitionRegistry)) {
                throw new IllegalStateException("Unsupported bean factory: " + factory.getClass().getTypeName());
            }
            BeanDefinitionRegistry registry = (BeanDefinitionRegistry) factory;

            String someBean = Arrays.stream(factory.getBeanNamesForType(SomeBeanType.class)).findFirst().orElseThrow();

            Arrays.stream(factory.getBeanNamesForType(SomeLegacyThing.class)).forEach(name -> {
                BeanDefinition definition = factory.getBeanDefinition(name);

                String value;
                if (definition instanceof AnnotatedBeanDefinition && definition.getSource() instanceof MethodMetadata) {
                    MethodMetadata beanMethod = (MethodMetadata) definition.getSource();
                    if (beanMethod.isAnnotated(SomeAdditionalData.class.getName())) {
                        Map<String, Object> attributes = beanMethod.getAnnotationAttributes(SomeAdditionalData.class.getName());
                        value = (IdentifikatorType) attributes.get("value");
                    } else {
                        throw new IllegalStateException("Bean " + name + " lacks " + SomeAdditionalData.class.getTypeName() + " annotation");
                    }
                } else {
                    throw new IllegalStateException("Unsupported declaration of bean " + name);
                }

                registry.registerBeanDefinition(
                    name + "BeanFactory",
                    BeanDefinitionBuilder
                        .genericBeanDefinition(NewStuffBeanFactory.class)
                        .setScope(BeanDefinition.SCOPE_SINGLETON)
                        .addConstructorArgReference(someBean)
                        .addConstructorArgReference(name)
                        .addConstructorArgValue(value)
                        .getBeanDefinition()
                );
            });
        };
    }
}