public function __construct($certificatesDir, $webRootDir, $logger = null, ClientInterface $client = null)
{
$this->certificatesDir = $certificatesDir;
$this->webRootDir = $webRootDir;
$this->logger = $logger;
$this->client = $client ? $client : new Client($this->ca);
$this->accountKeyPath = $certificatesDir . '/_account/private.pem';
}