I am using Spring Boot 2.2.4.RELEASE and I have this custom validator with an autowired service.
@Component
public class CompanyRequiredValidator implements ConstraintValidator<CompanyRequired, Company> {
    @Autowired
    private CompanyService companyService;
    @Override
    public void initialize(CompanyRequired constraintAnnotation) {
    }
    @Override
    public boolean isValid(Company company, ConstraintValidatorContext context) {
        return company != null && companyService.findByCompanyName(company.getCompanyName()) != null;
    }
}
My validation configuration.
@Configuration
public class ValidationConfig {
    @Bean
    public Validator validator() {
        return new LocalValidatorFactoryBean();
    }
    @Bean
    public MethodValidationPostProcessor methodValidationProstProcessor() {
        MethodValidationPostProcessor methodValidationPostProcessor = new MethodValidationPostProcessor();
        methodValidationPostProcessor.setValidator(validator());
        return methodValidationPostProcessor;
    }
}
No matter what I've tried the autowired field returns null. The things I've tried: