@NotNull
  public Collection<AbstractTreeNode<?>> createFileAndDirectoryNodes(@NotNull List<? extends VirtualFile> files, ViewSettings viewSettings) {
    final List<AbstractTreeNode<?>> children = new ArrayList<>(files.size());
    final PsiManager psiManager = PsiManager.getInstance(myProject);
    for (final VirtualFile virtualFile : files) {
      ContainerUtil.addIfNotNull(children, doCreateNode(virtualFile, psiManager, viewSettings));
    }
    return children;
  }
@NotNull
  public Collection<AbstractTreeNode<?>> createFileAndDirectoryNodes(@NotNull List<? extends VirtualFile> files, ViewSettings viewSettings)