private function getMailChimpLists()
    {
        $lists = [];

        // If Milchimp class doesn't exist or no key is set return empty list.
        if (!class_exists(\DrewM\MailChimp\MailChimp::class) || !$this->apiKey) {
            return $lists;
        }

        $mailChimp = new \DrewM\MailChimp\MailChimp($this->apiKey);
        $response = $mailChimp->get('lists', ['count' => 100]);

        if (!isset($response['lists'])) {
            return $lists;
        }

        foreach ($response['lists'] as $list) {
            $lists[] = [
                'id' => $list['id'],
                'name' => $list['name'],
            ];
        }

        return $lists;
    }