Only GET requests can be made to HubSpot's demo account. You can create a test account to try other methods (https://developers.hubspot.com/docs/faq/how-do-i-create-a-test-account)
Hubspot's article about the change: https://developers.hubspot.com/changelog/upcoming-changes-to-the-public-api-demo-account
I'm trying to create a new feature and then a pull request.
But hubspot is not being cooperative 
Should we create a test account for the specs of this gem?