src/ImageResponse.php
private function getImageStream()
    {
        return null !== $this->stream ? $this->stream :
            (null !== $this->image ? $this->stream = new ImageStream($this->image) : null);
    }
private function getImageStream()
    {
        return null !== $this->stream ? $this->stream :
            (null !== $this->image ? $this->stream = new ImageStream($this->image) : null);
    }
getImageStream

@return Psr\Http\Message\StreamInterface