*
   * <p>Builder instances can be reused; it is safe to call {@link #build} multiple times to build
   * multiple lists in series. Each new list contains all the elements of the ones created before
   * it.
   *
   * @since 2.0
   */
  public static final class Builder<E> extends ImmutableCollection.Builder<E> {
    // The first `size` elements are non-null.

   *
   * <p>Builder instances can be reused; it is safe to call {@link #build} multiple times to build
   * multiple lists in series. Each new list contains all the elements of the ones created before
   * it.
   *
   * @since 2.0
   */
  public static final class Builder<E> extends ImmutableCollection.ArrayBasedBuilder<E> {
    /**