curl --request GET \
  --url http://localhost:8000/api/v1/campaigns/drafts/{draft_id}/ad-groups/{ad_group_id}/rsas/{rsa_id} \
  --header 'Authorization: Bearer <token>'

{
  "id": 123,
  "ad_group_id": 123,
  "headlines": [
    {
      "text": "<string>",
      "reason": "<string>"
    }
  ],
  "descriptions": [
    {
      "text": "<string>",
      "reason": "<string>"
    }
  ],
  "final_url": "<string>",
  "final_mobile_url": "<string>",
  "display_path_1": "<string>",
  "display_path_2": "<string>",
  "tracking_url_template": "<string>",
  "generation_status": "pending",
  "generation_task_id": "<string>",
  "generation_error": "<string>"
}