public final boolean setCount(E element, int oldCount, int newCount) {
    throw new UnsupportedOperationException();
  }

  @GwtIncompatible // not present in emulated superclass
  @Override
  int copyIntoArray(@Nullable Object[] dst, int offset) {
    for (Multiset.Entry<E> entry : entrySet()) {
      Arrays.fill(dst, offset, offset + entry.getCount(), entry.getElement());
      offset += entry.getCount();

    }
    int[] result = new int[1]; // used as a mutable int reference to hold result
    AvlNode<E> newRoot = root.setCount(comparator(), element, count, result);
    rootReference.checkAndSet(root, newRoot);
    return result[0];
  }

  @CanIgnoreReturnValue
  @Override
  public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
    checkNonnegative(newCount, "newCount");

    }

    frequency.add(-numberRemoved);
    size -= numberRemoved;
    return oldCount;
  }

  // Roughly a 33% performance improvement over AbstractMultiset.setCount().
  @CanIgnoreReturnValue
  @Override
  public int setCount(@ParametricNullness E element, int count) {
    checkNonnegative(count, "count");

    Count existingCounter;
    int oldCount;
    if (count == 0) {

   *     zero instead.
   */
  @CanIgnoreReturnValue
  int setCount(@ParametricNullness E element, int count);

  /**
   * Conditionally sets the count of an element to a new value, as described in {@link
   * #setCount(Object, int)}, provided that the element has the expected current count. If the
   * current count is not {@code oldCount}, no change is made.
   *

    assertEquals(0, multiset.remove(entry.getElement(), entry.getCount()));
    assertFalse(multiset.remove(entry.getElement()));
    assertFalse(multiset.elementSet().remove(entry.getElement()));
  }

  void expectSetCountFailure(SortedMultiset<E> multiset, Entry<E> entry) {
    try {
      multiset.setCount(entry.getElement(), multiset.count(entry.getElement()));

    assertTrue(
        "setCount() with the correct expected present count should return true",
        setCount(element, count));
  }

  @Override
  void setCountNoCheckReturnValue(E element, int count) {
    setCount(element, count);
  }

  @CanIgnoreReturnValue
  private boolean setCount(E element, int count) {
    return getMultiset().setCount(element, getMultiset().count(element), count);
  }

    assertEquals(0, multiset.remove(entry.getElement(), entry.getCount()));
    assertFalse(multiset.remove(entry.getElement()));
    assertFalse(multiset.elementSet().remove(entry.getElement()));
  }

  void expectSetCountFailure(SortedMultiset<E> multiset, Entry<E> entry) {
    try {
      multiset.setCount(entry.getElement(), multiset.count(entry.getElement()));

    assertTrue(
        "setCount() with the correct expected present count should return true",
        setCount(element, count));
  }

  @Override
  void setCountNoCheckReturnValue(E element, int count) {
    setCount(element, count);
  }

  @CanIgnoreReturnValue
  private boolean setCount(E element, int count) {
    return getMultiset().setCount(element, getMultiset().count(element), count);
  }

    assertEquals(
        "multiset.setCount() should return the old count",
        getMultiset().count(element),
        setCount(element, count));
  }

  @Override
  void setCountNoCheckReturnValue(E element, int count) {
    setCount(element, count);
  }

  @CanIgnoreReturnValue
  private int setCount(E element, int count) {
    return getMultiset().setCount(element, count);
  }

   *     zero instead.
   */
  @CanIgnoreReturnValue
  int setCount(@ParametricNullness E element, int count);

  /**
   * Conditionally sets the count of an element to a new value, as described in {@link
   * #setCount(Object, int)}, provided that the element has the expected current count. If the
   * current count is not {@code oldCount}, no change is made.
   *