*/
  @CanIgnoreReturnValue
  public static <T extends @Nullable Object> boolean addAll(
      Collection<T> addTo, Iterator<? extends T> iterator) {
    checkNotNull(addTo);
    checkNotNull(iterator);
    boolean wasModified = false;
    while (iterator.hasNext()) {
      wasModified |= addTo.add(iterator.next());
    }
    return wasModified;
  }

  /**