public Optional<Output<ObjectFieldSelectorArgs>> fieldRef() {
        return Optional.ofNullable(this.fieldRef);
    }
@return Selects a field of the pod: supports metadata.name, metadata.namespace, `metadata.labels[&#39;&lt;KEY&gt;&#39;]`, `metadata.annotations[&#39;&lt;KEY&gt;&#39;]`, spec.nodeName, spec.serviceAccountName, status.hostIP, status.podIP, status.podIPs.
sdk/java/src/main/java/com/pulumi/kubernetes/core/v1/inputs/EnvVarSourceArgs.java