docs: public void removeAll() {
          int size = size();
          if (size == 0) {
              return;
          }
          for (int i = 0, listSize = lists.size(); i < listSize; i++) {
              List<? extends T> list = lists.get(i);
              if (list instanceof ObservableList) {
                  ((ObservableList) list).removeOnListChangedCallback(callback);
              }
          }
          lists.clear();
          modCount += 1;
          listeners.notifyRemoved(this, 0, size);
      }