public List<URL> transform(Collection<URL> urls, StandardTransform transform) {
        if (urls.isEmpty()) {
            return ImmutableList.of();
        }
        ClasspathFileTransformer transformer = fileTransformerFor(transform);
        return parallelTransformExecutor.transformAll(
            urls,
            (url, seen) -> cachedURL(url, transformer, seen, InstrumentationTypeRegistry.empty())
        );
    }