Exchanges client credentials (client ID and client secret) for an access token using HTTP Basic Authentication. The client ID is used as the username and the client secret as the password, encoded as Base64 in the format: Basic base64(clientId:clientSecret).Authorization is done using the “Basic” format within the “Authorization” header. Assuming client id is “sean@example.com” and client secret is “MyVeryCoolSecretPleaseDontSteal”, the format of the unencoded string is as follows: