public static void validateChildOf(Path root, Path path) {
        if (!path.normalize().startsWith(root)) {
            throw new IllegalArgumentException("Invalid path %s".formatted(path));
        }
    }
Validate that file is a child of basedir
@param root Root directory to use for validation
@param path Path to validate
@throws IllegalArgumentException if path is not a child of root
vespajlib/src/main/java/ai/vespa/validation/PathValidator.java