private HostSpec retire(HostSpec host) {
        return new HostSpec(host.hostname(),
                            host.realResources(),
                            host.advertisedResources(),
                            host.requestedResources().orElse(NodeResources.unspecified()),
                            host.membership().get().retire(),
                            host.version(),
                            Optional.empty(),
                            host.dockerImageRepo());
    }
Create a new provisioned instance to record provision requests to this and returns it
config-model/src/main/java/com/yahoo/config/model/provision/InMemoryProvisioner.java