def METHOD_NAME(self, challenge: str) -> str:  # pylint:disable=bad-option-value,useless-option-value,no-self-use
    """Verifies that the challenge is a valid auth challenge and returns the key=value pairs.
    :param str challenge: The WWW-Authenticate header of the challenge response.
    :returns: The challenge key/value pairs, with whitespace removed, as a string.
    :rtype: str
    """
    if not challenge:
        raise ValueError("Challenge cannot be empty")
    return challenge.strip()