curl --request POST \
  --url https://public-api-demo.clearline.me/v2/pos/{posSystemId}/widget/start \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json-patch+json' \
  --data '
{
  "posLocationId": "6orMqUyq2Hg3tP",
  "terminalId": "6orMqUyq",
  "widgetId": "1",
  "couponId": ""
}
'

{
  "data": {
    "sessionId": "<string>",
    "qrCodePreviewHtmlLinkUrl": "<string>"
  }
}