@Override
    protected List<String> getValidationErrors() {
        final List<String> errors = super.getValidationErrors();
        if (isCircleCheckBox.isSelected()) {
            if (!ValidationHelper.isPositiveInteger(radiusXTextField.getText()))
                errors.add("Radius should be positive integer number");
        } else {
            if (!ValidationHelper.isPositiveInteger(radiusXTextField.getText()))
                errors.add("RadiusX should be positive integer number");
            if (!ValidationHelper.isPositiveInteger(radiusYTextField.getText()))
                errors.add("RadiusY should be positive integer number");
        }
        return errors;
    }