private void authorize(final Authorization auth) throws Exception {
        val challenge = httpChallenge(auth);
        if (challenge.getStatus() != Status.VALID) {
            challenge.trigger();
            fetchStatusAndUpdate(challenge, challenge::getStatus);
            if (challenge.getStatus() != Status.VALID) {
                throw new AcmeException("Failed to pass the challenge for domain " + auth.getIdentifier().getDomain());
            }
        }
    }
Prepares a HTTP challenge.
<p>
The verification of this challenge expects a file with a certain content to be
reachable at a given path under the domain to be tested.

@param auth {@link Authorization} to find the challenge in
@return {@link Challenge} to verify
support/cas-server-support-acme/src/main/java/org/apereo/cas/acme/DefaultAcmeCertificateManager.java