@NotNull
 private Collection<DefaultMutableTreeNode> getSelectedNodes() {
   if (!isValid()) {
     return Collections.emptyList();
   }
   JTree tree = myStructureViewComponent.getTree();
   if (tree == null) return Collections.emptyList();
   TreePath[] selected = tree.getSelectionModel().getSelectionPaths();
   if (selected == null || selected.length == 0) return Collections.emptyList();
   return ContainerUtil.map(
       selected,
       new Function<TreePath, DefaultMutableTreeNode>() {
         @Override
         public DefaultMutableTreeNode fun(TreePath treePath) {
           return (DefaultMutableTreeNode) treePath.getLastPathComponent();
         }
       });
 }
  @Override
  public void saveDocument(@NotNull final Document document) {
    ApplicationManager.getApplication().assertIsDispatchThread();
    if (!myUnsavedDocuments.contains(document)) return;

    try {
      doSaveDocument(document);
    } catch (IOException e) {
      handleErrorsOnSave(Collections.singletonMap(document, e));
    } catch (SaveVetoException ignored) {
    }
  }