This endpoint is used to create access and refresh tokens.
When this endpoint is first called you must supply basic authentication credentials, your client_id and client_secret.
The response will contain an access_token and a refresh_token.
The access_token is used as a bearer token in most calls to Bud endpoints following this point.
To get a new access_token, you can use the refresh_token in a call to this endpoint. Your client_id will still be required, but it should be supplied as the header X-Client-Id.
You will need to do this once your access_token expires.