public function loginApplication()
    {
        $request = [
            'auth' => [
                $this->applicationKey,
                $this->applicationSecret,
            ],
            'headers' => [
                'Content-Type'  => 'application/json',
                'Accept'        => 'application/json',
            ],
            'json'  => [
                'application_bundle' => '',
            ],
        ];

        $url = $this->getRequestUrl().'/auth/login/application';

        $response = $this->getHttpClient()->post($url, $request);
        $response = json_decode($response->getBody());

        $this->connectionToken = $response->connection->token;

        return $this->connectionToken;
    }