public function setMimeType($mimeType)
    {
        if (!in_array($mimeType, $this->knownMimetypes)) {
            throw new UnsupportedParameterException("I cannot handle mimetype '$mimeType', only " . implode(',', $this->knownMimetypes ));
        }

        $this->mimeType = $mimeType;

        return $this;
    }