Example: Auth URL for code flow with offline token access type
https://www.dropbox.com/oauth2/authorize?client_id...
token_access_type String? If this parameter is set to offline, then the access token payload returned by a successful /oauth2/token call will contain a short-lived access_token and a long-lived refresh_token that can be used to request a new short-lived access token as long as a user's approval remains valid. If set to online then only a short-lived access_token will be returned. If omitted, this parameter defaults to online.