Class Validators errors are not reported in form.errors()

I`ve tested on such simple model and simple validator
Firma.java

        package models.validators;
        import javax.validation.Constraint;
        import javax.validation.Payload;
        import java.lang.annotation.Documented;
        import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
        import static java.lang.annotation.ElementType.TYPE;
        import java.lang.annotation.ElementType;
        import java.lang.annotation.Retention;
        import static java.lang.annotation.RetentionPolicy.RUNTIME;
        import java.lang.annotation.Target;


        @Target({ ElementType.TYPE, ANNOTATION_TYPE})
        @Retention(RUNTIME)
        @Constraint(validatedBy = FirmaValidator.class)
        @play.data.Form.Display(name="constraint.firma")
        @Documented
        public @interface Firma
        {
        String message() default "Please enter correct data"";

        Class<?>[] groups() default {};

        Class<? extends Payload>[] payload() default {};

        }

FirmaValidator.java

    package models.validators;
    import models.Osoba;
    import javax.validation.ConstraintValidator;
    import play.libs.F;

    public class FirmaValidator extends play.data.validation.Constraints.Validator<Object>
            implements ConstraintValidator<Firma, Object>
    {


        @Override
        public void initialize(final Firma constraintAnnotation)
        {

        }

        @Override
        public boolean isValid(Object value) {
            //returns false, just for tests 
            return false;
        }


        @Override
        public F.Tuple<String, Object[]> getErrorMessageKey() {
            return null;
        }

        /**
         * Constructs a validator instance.
         */
        public static play.data.validation.Constraints.Validator<Object> firma() {
            return new AllUpperCaseValidator();
        }
    }

Osoba.java

    package models;
    import models.validators.*;
    import org.joda.time.LocalDate;
    import org.joda.time.Years;
    import play.data.format.Formats;
    import play.data.validation.Constraints;
    import play.db.ebean.Model;

    import javax.persistence.*;
    import javax.validation.Valid;
    import javax.validation.constraints.NotNull;
    import java.util.Date;
    import java.util.Set;


    @Entity
    @Table(name = "osoby")
    // validator
    @Firma
    public class Osoba extends Model {
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        public Long   id;
        public Long getId() {
            return id;
        }

        public void setId(Long id) {
            this.id=id;
        }

        

    }

Now  my testcode:

    Form<Osoba> oform = Form.form(Osoba.class).bind(omap);
    System.out.print(oform.errors().values().toString());

Result should contain Firma error but it doesn`t. It`s bug or I`m missing something undocumented?