public static Endpoint.Builder sigv4a(
            Endpoint.Builder builder,
            List<Literal> signingRegionSet,
            Literal signingService
    ) {
        return builder.addAuthScheme(SIGV4A,
                MapUtils.of(
                        SIGNING_NAME,
                        signingService,
                        SIGNING_REGION_SET,
                        Literal.tupleLiteral(signingRegionSet)));
    }
Adds SigV4a authentication to the provided endpoint builder.

@param builder the endpoint builder to augment.
@param signingRegionSet the set of signing regions to use when signing.
@param signingService the name of the service to sign with.
@return the updated endpoint builder.
smithy-aws-endpoints/src/main/java/software/amazon/smithy/rulesengine/aws/language/functions/EndpointAuthUtils.java