'True if the credential is expired or invalid.
If the token_expiry isn\'t set, we assume the token doesn\'t expire.'

@property
def access_token_expired(self):

    if self.invalid:
        return True
    if (not self.token_expiry):
        return False
    now = _UTCNOW()
    if (now >= self.token_expiry):
        logger.info('access_token    is    expired.    Now:    %s,    token_expiry:    %s', now, self.token_expiry)
        return True
    return False
