I am currently trying to integrate Blackbaud's Payments API into a pre-existing platform to allow our customers to process transactions against the Payments API gateway. However, this integration will take the form of a server to server application where the “user,” would not have to interact with it at all. This means that the user would not be able to interact with the OAuth2 popup asking them to authorize the application. Is there any way that I could have the entire authorization flow happen in the backend?