OptionalchallengeChallengeStatus to convey to the client.
OptionaldecrementIf true, this request counts as one failed try and decrements remaining tries.
OptionalfailIf specified, challenge has failed permanently and server will return error.
OptionalparametersParameter key-value pairs to convey to the client.
OptionalsuccessIf true, challenge has succeeded and server will issue the certificate.
Result of challenge processing.