protected function getTransformerParam(DataTransformerInterface $transformer, $paramName)
    {
        $reflection = new \ReflectionProperty($transformer, $paramName);
        $reflection->setAccessible(true);
        $value  = $reflection->getValue($transformer);
        $result = null;

        if ('transformers' === $paramName && is_array($value)) {
            $result = $this->parseTransformers($value);
        } elseif (is_scalar($value) || is_array($value)) {
            $result = $value;
        } elseif ($value instanceof ChoiceListInterface) {
            $result = array_values($value->getChoices());
        }

        return $result;
    }