FormController.java

public class FormController extends AbstractFormController {

    private final Validator validator;

    private ValidatedValues<FormModel> v;

    public FormController(Validator validator) {
      this.validator = validator;
        v = ValidatedValues.build(FormModel.class).
                withProperty("firstName", () -> getFirstNameTextField().getText(), v -> updateForValidation(getFirstNameTextField(), v)).
                withProperty("lastName", () -> getLastNameTextField().getText(), v -> updateForValidation(getLastNameTextField(), v)).
                withProperty("active", () -> getActiveCheckBox().isSelected(), v -> updateForValidation(getActiveCheckBox(), v)).
                withProperty("gender", () -> getGenderChoiceBox().getValue(), v -> updateForValidation(getGenderChoiceBox(), v));
    }

    @Override
    protected void validate() {
        Set<ConstraintViolation<FormModel>> violations = validator.validate(v, UIGroup.class);

        if(violations == null || violations.isEmpty()) {
            System.out.println("We have no violations!");
            FormModel model = updateModelByUI();
            // Send model to server...

        } else {
            System.out.println("We have violations!");
            violations.forEach(v -> System.out.println(v.getMessage()));
        }
    }
}