MethodValidationPostProcessor and record configuration properties lead to IllegalArgumentException

[benfonty]

What happens

In a same Springboot project, we have a record configuration property:

@ConfigurationProperties(prefix = "myapp")
@Validated
public record MyProperties(@NotBlank String property) {}

If we want to enhance method level validation by creating a bean:

@Bean
public MethodValidationPostProcessor methodValidationPostProcessor() {
	return new MethodValidationPostProcessor();
}

Then when the application starts we have an exception java.lang.IllegalArgumentException: Cannot subclass final class com.example.demo.MyProperties.

It seems that Spring tries to make a cglib proxy for the record, which obviously won't work.

Minimal setup to reproduce

You will find a minimal setup to reproduce in this repo.

Work around

We found a workaround by explicitly removing the record:

public MethodValidationPostProcessor methodValidationPostProcessor() {
	return new MethodValidationPostProcessor() {
		@Override
		public boolean isEligible(Object bean, String beanName) {
			if (bean.getClass().isRecord()) {
				return false;
			}
			return super.isEligible(bean, beanName);
		}
	};
}

[snicoll]

This is the expected behavior I am afraid see https://docs.spring.io/spring-framework/reference/core/validation/beanvalidation.html#validation-beanvalidation-spring-method and some more discussion in spring-projects/spring-framework#27868