private long hash(File file, XXHash64 hasher) throws IOException {
        byte[] wholeFile = file.isDirectory() ?  new byte[0] : IOUtils.readFileBytes(file);
        return hasher.hash(ByteBuffer.wrap(wholeFile), hasher.hash(ByteBuffer.wrap(Utf8.toBytes(file.getName())), 0));
    }
Global file directory, holding files for file distribution for all deployed applications.
configserver/src/main/java/com/yahoo/vespa/config/server/filedistribution/FileDirectory.java