curl --request GET \
  --url https://your-instance.example.com/api/messages/webchat/{webchatId}

{
  "messages": [
    {
      "id": "<string>",
      "text": "<string>",
      "sender": "<string>",
      "timestamp": 123,
      "attachments": [
        {}
      ],
      "senderInfo": {
        "type": "<string>",
        "name": "<string>"
      }
    }
  ]
}