Zend\Diactoros\Stream::getMetadata PHP Method

    public function getMetadata($key = null)
    {
        if (null === $key) {
            return stream_get_meta_data($this->resource);
        }
        $metadata = stream_get_meta_data($this->resource);
        if (!array_key_exists($key, $metadata)) {
            return null;
        }
        return $metadata[$key];
    }