Check if refresh token is decodable before decoding it

            return False

        if not custos_authnz_token.refresh_token:

            return False

        # Try to extract expiration date from the refresh token. If expired, do not refresh token.

        try: 

            refresh_token_decoded = self._decode_token_no_signature(custos_authnz_token.refresh_token)

            # do not attempt to use refresh token that is already expired

            if int(refresh_token_decoded["exp"]) <= int(time.time()):

                # in the future we might want to log out the user here

                return False

        except jwt.exceptions.DecodeError:

            log.error("Refresh token is non-decodable")

        oauth2_session = self._create_oauth2_session()

        token_endpoint = self.config.token_endpoint

        if self.config.iam_client_secret: