public function json() : string
    {
        return json_encode([
            'title' => $this->title,
            'body' => $this->body,
            'url' => $this->url,
            'icon' => $this->icon,
        ]);
    }
public function json() : string
    {
        return json_encode([
            'title' => $this->title,
            'body' => $this->body,
            'url' => $this->url,
            'icon' => $this->icon,
        ]);
    }
public function json ( ) : string { return json_encode ( [ 'title' => $ this -> title , 'body' => $ this -> body , 'url' => $ this -> url , 'icon' => $ this -> icon , ] ) ; }
Convert the push notification into a json string.

@return string
Convert the push notification into a json string .