public Optional<String> controller() {
        return Optional.ofNullable(this.controller);
    }
@return controller refers to the name of the controller that should handle this class. This allows for different &#34;flavors&#34; that are controlled by the same controller. For example, you may have different parameters for the same implementing controller. This should be specified as a domain-prefixed path no more than 250 characters in length, e.g. &#34;acme.io/ingress-controller&#34;. This field is immutable.
sdk/java/src/main/java/com/pulumi/kubernetes/networking/v1/outputs/IngressClassSpecPatch.java