public Optional<SecretReferencePatch> secretRef() {
        return Optional.ofNullable(this.secretRef);
    }
@return secretRef is Optional: SecretRef is reference to the authentication secret for User, default is empty. More info: https://examples.k8s.io/volumes/cephfs/README.md#how-to-use-it
sdk/java/src/main/java/com/pulumi/kubernetes/core/v1/outputs/CephFSPersistentVolumeSourcePatch.java