Spring validation with inheritance

I'm trying to validate a DTO (formModel, whatever term you prefer) which is a bit layered (inheritance and dependencies to other classes).

Is it possible to get the following configuration of models to work:

public abstract class A {

    @NotNull
    private String fieldA1;

    @NotNull
    @Size(min = 2, max = 30)
    private String fieldA2;

    // ... and so on

}


public class B extends A {

    @NotNull
    private String fieldB1;

    @NotNull
    private Xyz fieldB2;

    // and so on
}


public class Xyz {

    @NotNull
    private String fieldXyz1;

    // etc..
}

Spring rest controller:

@PostMapping(consumes = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity addCustomer(@RequestBody @Valid B customerDto, BindingResult bindingResult) {
// controller logic here
}

The problem is: only constraint annotations that seem to "work" are those on the parent class A. I submit a request with bad fields in the class A, bindingResult.hasErrors() returns true. If I submit a request with bad fields in classes B or Xyz, bindingResult.hasErrors() is false and the controller just goes on behaving like the request is ok. Any ideas why?