@Override
  public AsynchronousFileChannel newAsynchronousFileChannel(
      Path path,
      Set<? extends OpenOption> options,
      @Nullable ExecutorService executor,
      FileAttribute<?>... attrs)
      throws IOException {
    // call newFileChannel and cast so that FileChannel support is checked there
    JimfsFileChannel channel = (JimfsFileChannel) newFileChannel(path, options, attrs);
    if (executor == null) {
      JimfsFileSystem fileSystem = (JimfsFileSystem) path.getFileSystem();
      executor = fileSystem.getDefaultThreadPool();
    }
    return channel.asAsynchronousFileChannel(executor);
  }
Returns the default file system view for the given path.
jimfs/src/main/java/com/google/common/jimfs/JimfsFileSystemProvider.java