@Override
  @Nullable
  protected String showDialog() {
    ClassFilter.ClassFilterWithScope classFilter;
    try {
      classFilter = getFilter();
    }
    catch (NoFilterException e) {
      e.getMessageInfo().showNow();
      return null;
    }

    TreeClassChooser dialog = createClassChooser(classFilter);
    ((AbstractTreeClassChooserDialog<?>)dialog).setInitialSelection(objects -> findClass(getText()));
    dialog.showDialog();
    PsiClass psiClass = dialog.getSelected();
    if (psiClass == null) return null;
    onClassChosen(psiClass);
    return psiClass.getQualifiedName();
  }
@Override
  @Nullable
  protected String showDialog()