code: public void init() throws IOException {
      if (!Files.exists(path)) {
        throw new FileNotFoundException(
            "Could not find a file under path: " + path.toAbsolutePath().toString());
      }
      if (Files.size(path) == 0) {
        throw new IllegalStateException("File size can't be zero for chunked files");
      }
      chunks = chunkFile();
      chunksInUse = new ConcurrentSkipListMap<>();
      chunksPreRead = new ConcurrentSkipListMap<>();
      chunksScheduled = new ConcurrentSkipListMap<>();
      nextChunkNum = new AtomicInteger(-1);
      if (raf != null) {
        raf.close();
      }
      execIo = MoreExecutors.listeningDecorator(Executors.newSingleThreadExecutor());
      execFinalize = Executors.newSingleThreadExecutor();
    }
docs: Check if the file is still valid.