@Override
    public Path addFile(Path path) {
        if (!path.startsWith(baseDir) || !path.isAbsolute()) {
            path = resolvePath(path);
        }

        files.put(path, new byte[0]);
        return path;
    }
Creates a mock manifest that stores files in memory and uses a
base directory of "/".
smithy-build/src/main/java/software/amazon/smithy/build/MockManifest.java