code: public void move(String sourceDir, String targetDir) throws IOException {
      validatePathname(sourceDir);
      validatePathname(targetDir);
  
      Files.move(
          Paths.get(getStorageDir() + File.separator + sourceDir),
          Paths.get(getStorageDir() + File.separator + targetDir));
    }
docs: Move directories in FileStore Pleae provide the path from the relative root of the fileStore
  
  <p>So if you want to move a top-level directory the following syntax is sufficient: <code>
  move("dir1", "dir2");
  </code> Sub-level directory can be moved by typing: <code>
  move("dir1/subdir1", "dir2/subdir1");
  </code> Make sure the top-level directories are existing
  
  @param sourceDir directory yo want to move
  @param targetDir target directory you want to move to
  @throws IOException