public Optional<String> secretFile() {
        return Optional.ofNullable(this.secretFile);
    }
@return secretFile is Optional: SecretFile is the path to key ring for User, default is /etc/ceph/user.secret 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/CephFSPersistentVolumeSource.java