title: vaadin 8 FilesystemContainer alternative
body: <p>I used FilesystemContainer in a Vaadin 7 application to populate the contents of a com.vaadin.ui.Tree for viewing and selecting files on the server.</p>
  
  <pre><code>tree.setContainerDataSource (new FilesystemContainer (new File ("o: \\")));
  </code></pre>
  
  <p>However, when migrating this application to Vaadin 8 I did not find an alternative to the FilesystemContainer. Could anyone tell me which way would be the best?</p>