private synchronized List<T> syncInitList(@NotNull CefBrowser browser, @NotNull Runnable onInit) {
      List<T> list = myMap.get(browser);
      if (list == null) {
        if (myMap.isEmpty()) {
          onInit.run();
        }
        myMap.put(browser, list = Collections.synchronizedList(new LinkedList<>()));
      }
      return list;
    }
private synchronized List<T> syncInitList(@NotNull CefBrowser browser, @NotNull Runnable onInit)