public static HostProvisionerProvider withProvisioner(Provisioner provisioner, ConfigserverConfig config) {
        ComponentRegistry<Provisioner> registry = new ComponentRegistry<>();
        registry.register(ComponentId.createAnonymousComponentId("foobar"), provisioner);
        return new HostProvisionerProvider(registry, config);
    }
Returns the host provisioner, or empty if we are not in hosted mode
configserver/src/main/java/com/yahoo/vespa/config/server/provision/HostProvisionerProvider.java