Uuid newAclId() {
        Uuid uuid;
        do {
            uuid = Uuid.randomUuid();
        } while (idToAcl.containsKey(uuid));
        return uuid;
    }
The AclControlManager manages any ACLs that are stored in the __cluster_metadata topic.
If the ACLs are stored externally (such as in ZooKeeper) then there will be nothing for
this manager to do.
metadata/src/main/java/org/apache/kafka/controller/AclControlManager.java