void addFileLevelComponent(@NotNull FileEditor fileEditor, @NotNull JComponent component) {
    if (fileLevelComponentsStorage == null) {
      fileLevelComponentsStorage = new Pair<>(fileEditor, component);
    }
    else if (fileLevelComponentsStorage instanceof Pair) {
      //noinspection unchecked
      Pair<FileEditor, JComponent> pair = (Pair<FileEditor, JComponent>)fileLevelComponentsStorage;
      Map<FileEditor, JComponent> map = new HashMap<>();
      map.put(pair.first, pair.second);
      map.put(fileEditor, component);
      fileLevelComponentsStorage = map;
    }
    else if (fileLevelComponentsStorage instanceof Map) {
      //noinspection unchecked
      ((Map<FileEditor, JComponent>)fileLevelComponentsStorage).put(fileEditor, component);
    }
    else {
      LOG.error(new IllegalStateException("fileLevelComponents=" + fileLevelComponentsStorage));
    }
  }
void addFileLevelComponent(@NotNull FileEditor fileEditor, @NotNull JComponent component)