public Optional<LocalObjectReference> secretRef() {
        return Optional.ofNullable(this.secretRef);
    }
@return secretRef is name of the authentication secret for RBDUser. If provided overrides keyring. Default is nil. More info: https://examples.k8s.io/volumes/rbd/README.md#how-to-use-it
sdk/java/src/main/java/com/pulumi/kubernetes/core/v1/outputs/RBDVolumeSource.java