* is iterated are the individual lists created, and these are not retained after iteration.
   *
   * @param lists the lists to choose elements from, in the order that the elements chosen from
   *     those lists should appear in the resulting lists
   * @param <B> any common base class shared by all axes (often just {@link Object})

     *
     * <ul>
     *   <li>For an empty list, it is 1 (base case).
     *   <li>When r numbers are added to a list of n-r elements, the number of permutations is
     *       increased by a factor of (n choose r).
     * </ul>
     */
    private static <E> int calculateSize(
        List<E> sortedInputList, Comparator<? super E> comparator) {
      int permutations = 1;
      int n = 1;
      int r = 1;

     * {@link Session#resolveDependencies resolveDependencies(...)} when at least one dependency
     * cannot be associated to any type specified in the {@code desiredTypes} argument.
     * Plugins can choose to report a warning to users when unresolved paths exist.
     */
    PathType UNRESOLVED = new PathType() {
        @Override
        public String name() {
            return "UNRESOLVED";
        }

   *
   * @deprecated If you must interoperate with a system that requires MD5, then use this method,
   *     despite its deprecation. But if you can choose your hash function, avoid MD5, which is
   *     neither fast nor secure. As of January 2017, we suggest:
   *     <ul>
   *       <li>For security:
   *           {@link Hashing#sha256} or a higher-level API.

   * iterated are the individual lists created, and these are not retained after iteration.
   *
   * @param sets the sets to choose elements from, in the order that the elements chosen from those
   *     sets should appear in the resulting lists
   * @param <B> any common base class shared by all axes (often just {@link Object})

     *
     * <ul>
     *   <li>For an empty list, it is 1 (base case).
     *   <li>When r numbers are added to a list of n-r elements, the number of permutations is
     *       increased by a factor of (n choose r).
     * </ul>
     */
    private static <E> int calculateSize(
        List<E> sortedInputList, Comparator<? super E> comparator) {
      int permutations = 1;
      int n = 1;
      int r = 1;

   */
  // TODO(fry): empirically optimize this
  static final int DRAIN_MAX = 16;

  // Fields

  /**
   * Mask value for indexing into segments. The upper bits of a key's hash code are used to choose
   * the segment.
   */
  final transient int segmentMask;

  /**
   * Shift value for indexing within segments. Helps prevent entries that end up in the same segment

       * run the supermethod as usual.
       *
       * TODO: b/292578973: Use @AndroidIncompatible if we change our system to keep the methods in
       * place but to have the test runner skip them. However, note that if we choose to *both*
       * strip the methods *and* have the test runner not run them (for some unusual cases in which
       * we don't run the stripping test for technical reasons), then we'd be back to the problem

       * run the supermethod as usual.
       *
       * TODO: b/292578973: Use @AndroidIncompatible if we change our system to keep the methods in
       * place but to have the test runner skip them. However, note that if we choose to *both*
       * strip the methods *and* have the test runner not run them (for some unusual cases in which
       * we don't run the stripping test for technical reasons), then we'd be back to the problem

            .flatMap(x -> x);
    assertThat(concatenated).containsExactly("a", "b", "c", "d").inOrder();
    concatenated.close();
    // even without close, see doc for flatMap
    assertThat(closeCountB.get()).isEqualTo(1);
  }

  public void testConcat_refStream_closeIsPropagated_exceptionsChained() {