* ImmutableMultiset#builder}.
     */
    public Builder() {
      this(LinkedHashMultiset.<E>create());
    }

    Builder(Multiset<E> contents) {
      this.contents = contents;
    }

    /**
     * Adds {@code element} to the {@code ImmutableMultiset}.
     *
     * @param element the element to add
     * @return this {@code Builder} object
     * @throws NullPointerException if {@code element} is null

    ExpiringMemoizingSupplier(Supplier<T> delegate, long durationNanos) {
      this.delegate = delegate;
      this.durationNanos = durationNanos;
    }

    @Override
    @ParametricNullness
    public T get() {
      // Another variant of Double Checked Locking.
      //
      // We use two volatile reads. We could reduce this to one by
      // putting our fields into a holder class, but (at least on x86)

    return new Joiner(String.valueOf(separator));
  }

  private final String separator;

  private Joiner(String separator) {
    this.separator = checkNotNull(separator);
  }

  private Joiner(Joiner prototype) {
    this.separator = prototype.separator;
  }

  /*
   * In this file, we use <? extends @Nullable Object> instead of <?> to work around a Kotlin bug

     * filesystem) does our prod code look up the username. Thus, this test doesn't necessarily test
     * anything interesting under most environments. Still, we can run it (except for Android, at
     * least old versions), so we mostly do. This is useful because we don't actually run our CI on
     * Windows under Java 8, at least as of this writing.
     *
     * Under Windows in particular, we want to test that:
     *

 *       have, of returning a new, independent iterator
 * </ul>
 *
 * <p>Because of this situation, any public method accepting an iterable should invoke the {@code
 * iterator} method only once, and should be tested using this class. Exceptions to this rule should
 * be clearly documented.
 *
 * <p>Note that although your APIs should be liberal in what they accept, your methods which

  }

  /**
   * Returns {@code true} if this BiMap contains an entry whose value is equal to {@code value} (or,
   * equivalently, if this inverse view contains a key that is equal to {@code value}).
   *
   * <p>Due to the property that values in a BiMap are unique, this will tend to execute in
   * faster-than-linear time.
   *
   * @param value the object to search for in the values of this BiMap

    return Lists.newArrayList(0);
  }

  /**
   * The version of this test supplied by {@link MapInterfaceTest} fails for this particular Map
   * implementation, because {@code map.get()} returns a view collection that changes in the course
   * of a call to {@code remove()}. Thus, the expectation doesn't hold that {@code map.remove(x)}

   * situations, you may wish to override {@link SortedMultiset#elementSet} to forward to this
   * implementation or a subclass thereof.
   */
  protected class StandardElementSet extends SortedMultisets.ElementSet<E> {
    /** Constructor for use by subclasses. */
    public StandardElementSet() {
      super(ForwardingSortedMultiset.this);
    }
  }

  @Override
  public Comparator<? super E> comparator() {

    final Comparator<? super E> comparator;
    final int size;

    OrderedPermutationCollection(Iterable<E> input, Comparator<? super E> comparator) {
      this.inputList = ImmutableList.sortedCopyOf(comparator, input);
      this.comparator = comparator;
      this.size = calculateSize(inputList, comparator);
    }

    /**
     * The number of permutations with repeated elements is calculated as follows:
     *

    // entry object per key.
    private ValueSetLink<K, V> firstEntry;
    private ValueSetLink<K, V> lastEntry;

    ValueSet(@ParametricNullness K key, int expectedValues) {
      this.key = key;
      this.firstEntry = this;
      this.lastEntry = this;
      // Round expected values up to a power of 2 to get the table size.
      int tableSize = Hashing.closedTableSize(expectedValues, VALUE_SET_LOAD_FACTOR);