protected function validateConfig($key, array $configuration, $isFloat = false)
    {
        if (!$isFloat && !ctype_digit((string) $configuration[$key])) {
            throw new ValidationException(sprintf('"%s" is not a valid %s configuration', $configuration[$key], $key));
        }

        if ($isFloat && !is_numeric((string) $configuration[$key])) {
            throw new ValidationException(sprintf('"%s" is not a valid %s configuration', $configuration[$key], $key));
        }

        return true;
    }