How to register dynamic JPA entities and repositories before Spring context loads using ByteBuddy?

Question

I am attempting to dynamically create a JPA entity and its corresponding repository using ByteBuddy before the Spring context is fully loaded. My goal is to use the dynamically generated entity and repository during runtime.

Here's the configuration I've set up to register the JPA entity and repository:

@Configuration
public class DynamicJpaBeanFactoryPostProcessor implements BeanFactoryPostProcessor, BeanDefinitionRegistryPostProcessor {

    private Class<?> entityClass;

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        entityClass = generateCustomerClass();
        String entityBeanName = "it.example.entity.Customer";

        AbstractBeanDefinition entityBeanDefinition = BeanDefinitionBuilder.genericBeanDefinition(entityClass).getBeanDefinition();
        registry.registerBeanDefinition(entityBeanName, entityBeanDefinition);
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        registerRepository(beanFactory, entityClass);
    }


    private void registerRepository(ConfigurableListableBeanFactory configurableListableBeanFactory, Class<?> entityClass) {
        TypeDescription.Generic repositoryTypeDescription =
                TypeDescription.Generic.Builder.parameterizedType(
                        JpaRepository.class, entityClass, Integer.class).build();

        // genero repository
        String repositoryBeanName = "it.example.repositories.DynamicCustomerRepository";

        new ByteBuddy()
                .makeInterface(repositoryTypeDescription)
                .name(repositoryBeanName)
                .annotateType(AnnotationDescription.Builder.ofType(Repository.class).build())
                .make()
                .load(getClass().getClassLoader(), ClassLoadingStrategy.Default.INJECTION)
                .getLoaded();

        BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder
                .rootBeanDefinition(JpaRepositoryFactoryBean.class).addConstructorArgValue(repositoryBeanName);

        ((DefaultListableBeanFactory) configurableListableBeanFactory)
                .registerBeanDefinition(repositoryBeanName, beanDefinitionBuilder.getBeanDefinition());
    }


    // ... Additional methods (generateCustomerClass) ...
}

I then attempt to use my generated repository in another class:

@Component
class CustomersUsage {
@Autowired
ApplicationContext applicationContext;

    public String test() {
        JpaRepository<?, ?> repository = (JpaRepository<?, ?>) applicationContext.getBean("it.example.repositories.DynamicCustomerRepository");
        return "";
    }

However, I encounter the following error:

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.format.support.FormattingConversionService]: Factory method 'mvcConversionService' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'it.example.repositories.DynamicCustomerRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class it.example.entity.Customer

This error does not occur when the entity class is physically present before Spring starts (i.e., it is not generated at runtime), and the repository works as expected.

It seems that the dynamically generated entity is not being recognized as a managed JPA entity, which is likely why the repository is failing.

How can I properly register my dynamically generated JPA entity so that the repository will recognize it as a managed type?