public function attach()
    {
        $parameters = [
            'return_url' => $this->getCurrentUrl(),
            'broker' => $this->brokerName,
            'token' => $this->token,
            'checksum' => hash('sha256', 'attach' . $this->token . $this->brokerSecret)
        ];

        $attachUrl = $this->generateCommandUrl('attach', $parameters);

        $this->redirect($attachUrl);
    }