public Optional<Output<Map<String,List<String>>>> extra() {
        return Optional.ofNullable(this.extra);
    }
@return extra contains extra attributes of the user that created the CertificateSigningRequest. Populated by the API server on creation and immutable.
sdk/java/src/main/java/com/pulumi/kubernetes/certificates/v1/inputs/CertificateSigningRequestSpecArgs.java