public Builder<E> addAll(Iterator<? extends E> elements) {
      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue
    Builder<E> combine(Builder<E> other) {
      addAll(other.contents, other.size);
      return this;
    }

    /**
     * Returns a newly-created {@code ImmutableList} based on the contents of the {@code Builder}.
     */
    @Override