Custom Validation message is not working with Spring Boot 3

Question

I am using Spring boot 3 Rest Api, with spring-validation-starter.
Even after configuring Message Source and LocalValidatorFactoryBean, as follows

    @Bean
    @Primary
    public MessageSource messageSource() {
        ReloadableResourceBundleMessageSource resourceBundleMessageSource= new ReloadableResourceBundleMessageSource();
        resourceBundleMessageSource.setBasenames("classpath:messages"); // directory with messages_XX.properties
        resourceBundleMessageSource.setUseCodeAsDefaultMessage(false);
        //resourceBundleMessageSource.setDefaultLocale(Locale.ENGLISH);
        resourceBundleMessageSource.setDefaultEncoding("UTF-8");
        resourceBundleMessageSource.setAlwaysUseMessageFormat(true);
        return resourceBundleMessageSource;
    }


    @Bean
    @Primary
    public LocalValidatorFactoryBean validator(MessageSource messageSource) {
        LocalValidatorFactoryBean bean = new LocalValidatorFactoryBean();
        bean.setValidationMessageSource(messageSource);
        return bean;
    }

    @Bean
    public LocaleResolver localResolver()
    {
        SessionLocaleResolver sessionLocaleResolver = new SessionLocaleResolver();
        sessionLocaleResolver.setDefaultLocale(Locale.US);
        return sessionLocaleResolver;
    }

and the DTO as

@Getter
@Setter
public class UserInvitationRequest {

    @NotEmpty(message = "{email.not.empty}")
    String email;

    @NotNull
    UserType userType;

}

where my message.properties has
email.not.empty=Email cannot be blank

the validation message is not resolved properly, and returning the default validation message provided by jakarta.validation as "must not be null"

I assume the message properties are not getting registered with the validation framework.
Am I doing some thing wrong ?

on validation error, the following should return

ex.getBindingResult().getFieldErrors().getField().getDefaultMessage()  // Translated message from messages.properties.

instead of

ex.getBindingResult().getFieldErrors().getField().getDefaultMessage() //"must not be null"