public function unsubscribe($applicationName, $eventSource)
    {
        $uri = "applications/$applicationName/subscription?eventSource=".\GuzzleHttp\json_encode($eventSource);
        try {
            $response = $this->client->getEndpoint()->delete($uri);
        } catch (RequestException $e) {
            $this->processRequestException($e);
        }

        return new Application($this->client, \GuzzleHttp\json_decode($response->getBody()));
    }