@Contract(mutates = "param1")
  public static <T> void addAll(@NotNull Collection<? super T> collection, @NotNull Iterable<? extends T> appendix) {
    addAll(collection, appendix.iterator());
  }
@Contract(mutates = "param1")
  public static <T> void addAll(@NotNull Collection<? super T> collection, @NotNull Iterable<? extends T> appendix)