protected function _getValidationErrors($subject)
    {
        $errors = array();
        foreach ($this->_getChildValidators() as $_idx => $_validator) {
            try {
                if (!($_validator instanceof ValidatorInterface)) {
                    throw $this->_createOutOfRangeException($this->__('Validator %1$s is invalid', array($_idx)), null, null, $_validator);
                }

                $_validator->validate($subject);
            } catch (ValidationFailedExceptionInterface $e) {
                $errors[] = $e->getValidationErrors();
            }
        }

        return $this->_normalizeErrorList($errors);
    }