curl --request POST \
  --url https://your-instance.example.com/api/conversation/{conversationId}/send-message \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "body": "<string>",
  "attachments": [
    {
      "filename": "<string>",
      "url": "<string>",
      "contentType": "<string>"
    }
  ],
  "isInternal": true
}
'

{
  "success": true,
  "message": {}
}