Solve error Field <com.JdkClientHttpRequestFactoryConfiguration$$SpringCGLIB$$0.$$beanFactory> does not have modifier PRIVATE in (<generated>:0)

Question

I would like to write an ArchUnit rule which check that classes annotated with @Configuration in Spring does not have any fields that are PUBLIC.

For instance, this class should be OK, there is no field at all:

@Configuration
@EnableWebSecurity
class SecurityConfiguration {

    @Bean
    SecurityFilterChain securityFilterChain(final HttpSecurity httpSecurity) throws Exception {
        httpSecurity.authorizeHttpRequests(authorize -> authorize.anyRequest().permitAll()).csrf(AbstractHttpConfigurer::disable);
        return httpSecurity.build();
    }

}

This class should also be OK; there is a field, but it is private static final:

@Configuration
class JdkClientHttpRequestFactoryConfiguration {
    
    private static final int DEFAULT_READ_TIMEOUT = 5;

    @Bean
    JdkClientHttpRequestFactory jdkClientHttpRequestFactory() {
        final JdkClientHttpRequestFactory jdkClientHttpRequestFactory = new JdkClientHttpRequestFactory();
        jdkClientHttpRequestFactory.setReadTimeout(Duration.ofSeconds(DEFAULT_READ_TIMEOUT));
        return jdkClientHttpRequestFactory;
    }

}

And fail if any public fields.

I tried this rule:

@Test
void fieldShouldAllBePrivateToProtectEncapsulation() {
    fields().that(areNotConfiguration())
            .and().areNotStatic()
            .and().areNotFinal()
            .should().bePrivate()
            .check(importedClasses);
}

private DescribedPredicate<? super JavaField> areNotConfiguration() {
    return new DescribedPredicate<>("are not @Configuration") {
        @Override
        public boolean test(JavaField javaField) {
            JavaClass owner = javaField.getOwner();
            return !owner.isAnnotatedWith(Configuration.class) || !javaField.getRawType().isAssignableTo(owner.reflect());
        }
    };
}

However, it yields this very strange kind of failure:

JdkClientHttpRequestFactoryConfiguration$$SpringCGLIB$$0.$$beanFactory> does not have modifier PRIVATE in (:0)

SecurityConfiguration$$SpringCGLIB$$FastClass$$1.$$beanFactory> does not have modifier PRIVATE in (:0)

May I ask how to properly write the ArchUnit rule for classes with @Configuration?