public function toArray()
    {
        return array_filter(
            array(
                'method' => $this->getMethod(),
                'url' => $this->getUrl(),
                'headers' => $this->getHeaders(),
                'body' => $this->getBody(),
                'post_files' => $this->getPostFiles(),
                'post_fields' => $this->getPostFields(),
            )
        );
    }