@Override
  public void move(Path srcPath, SecureDirectoryStream<Path> targetDir, Path targetPath)
      throws IOException {
    checkOpen();
    JimfsPath checkedSrcPath = checkPath(srcPath);
    JimfsPath checkedTargetPath = checkPath(targetPath);

    if (!(targetDir instanceof JimfsSecureDirectoryStream)) {
      throw new ProviderMismatchException(
          "targetDir isn't a secure directory stream associated with this file system");
    }

    JimfsSecureDirectoryStream checkedTargetDir = (JimfsSecureDirectoryStream) targetDir;

    view.copy(
        checkedSrcPath,
        checkedTargetDir.view,
        checkedTargetPath,
        ImmutableSet.<CopyOption>of(),
        true);
  }
A stream filter that always returns true.
jimfs/src/main/java/com/google/common/jimfs/JimfsSecureDirectoryStream.java