throw new UnsupportedOperationException();
        }
    }

    private static class SystemIncludeFile extends CachedIncludeFile implements IncludeFile {
        final File file;
        final String includePath;
        final HashCode contentHash;

        SystemIncludeFile(File file, String includePath, HashCode contentHash) {
            this.file = file;
            this.includePath = includePath;