Hibernate method validation NOT always working

Why is Hibernate's validation - ConstraintViolationException - NOT thrown in main() of a SpringBoot app (SpringBoot's latest version) with spring-boot-starter-web:

@Validated
@SpringBootApplication
public class Application {
public static void main(String[] args) {
   SpringApplication.run(Application.class, args);
   someService.doStuff(new Item(null);  // WHY NOT THROWN????????!!!!!! 
   // Expecting ConstraintViolationException: doStuff.item.content: must not be null
}}
// ----------------------

public class Item {
    @NotNull
    String content;  // to be validated
   //constructor, getter, setter
}

@Validated
@Service
public class SomeService {
    void doStuff(@Valid Item item) {} // should break for Item's content = null
}

Strangely enough, in other cases Hibernate validation is working as expected for the same method call:

1. ConstraintViolationException is thrown when I put the invalid call in a controller's contructor:

public SomeController(SomeService someService){
    this.someService = someService;
    someService.doStuff(new Item(null); // throws ConstraintViolationException  
}

2. Also as expected, ConstraintViolationException is thrown when I put the invalid call in a constructor method and call the endpoint in a test or Postman

@GetMapping("item")
public String item() {
    someService.doStuff(new Item(null); // throws ConstraintViolationException
    return "You never get here.";
}

Not sure how are you getting someService instance in Application, but the following code works for me (every class in a different file):

@AllArgsConstructor
@Getter
@Setter
public class Item {

  @NotNull
  String content;
}



@Validated
@Service
public class SomeService {

  public void doStuff(@Valid Item item) {
    System.out.println(format("Item.content = %s", item.getContent()));
  }
}



@SpringBootApplication
public class TestingPurposeApplication {

  public static void main(String[] args) {
    ConfigurableApplicationContext context = SpringApplication.run(TestingPurposeApplication.class, args);
    SomeService someService = context.getBean(SomeService.class);
    someService.doStuff(new Item(null));
  }
}

The result:

Use:

ConfigurableApplicationContext context = SpringApplication.run(MyApplication.class, args);
MyClass myInstance = context.getBean(MyClass.class);

Is the suitable way to get a component managed by Spring in main method.