public Optional<List<String>> getSigv4aRegionSet() {
        return Optional.ofNullable(sigv4aRegionSet);
    }
@return The set of regions to sign a sigv4a request with, if present.
smithy-aws-smoke-test-model/src/main/java/software/amazon/smithy/aws/smoketests/model/BaseAwsVendorParams.java