private void updateFile() {
    String uri = generateFromUrl.getText();
    boolean hasPrevious = (previousUri != null && previousUri.equals(uri));
    final PsiFile psifile = findFile(uri);
    List<String> myRootValues;

    if (psifile == null) {
      configureComboBox(rootElementChooser, Collections.emptyList());
      return;
    }

    final XmlTag rootTag = getRootTag(psifile);

    if (rootTag == null) {
      configureComboBox(rootElementChooser, Collections.emptyList());
      rootElementChooser.setSelectedIndex(-1);
      previousUri = uri;
      return;
    }

    myRootValues = Xsd2InstanceUtils.addVariantsFromRootTag(rootTag);

    Object selectedItem = rootElementChooser.getSelectedItem();
    configureComboBox(rootElementChooser, myRootValues);

    if (hasPrevious) {
      rootElementChooser.setSelectedItem(selectedItem);
    }
    else {
      rootElementChooser.setSelectedIndex(myRootValues.size() > 0 ? 0 : -1);
    }
    previousUri = uri;
  }
private void updateFile()