// Returns itself as the renewed credentials
            return this;
        }
    }

    static class NewRenewingCreds extends BaseCreds {
        @Override
        public CredentialsInternal renew() {
            // Returns a distinct, new credentials instance
            return new NewRenewingCreds();
        }
    }

    static class NullRenewingCreds extends BaseCreds {
        @Override