public static FullIntList newInstance(@NotNull IntList delegateList) {
    int[] list = new int[delegateList.size()];
    for (int i = 0; i < list.length; i++) {
      list[i] = delegateList.get(i);
    }
    return new FullIntList(list);
  }
public static FullIntList newInstance(@NotNull IntList delegateList)