* cancelled without a call to {@code cancel}, such as by calling {@code
   * setFuture(cancelledFuture)}.
   *
   * <p>Beware of completing a future while holding a lock. Its listeners may do slow work or
   * acquire other locks, risking deadlocks.
   */
  @CanIgnoreReturnValue
  @Override
  public boolean cancel(boolean mayInterruptIfRunning) {
    Object localValue = value;
    boolean rValue = false;

  Striped64() {}

  /** CASes the base field. */
  final boolean casBase(long cmp, long val) {
    return UNSAFE.compareAndSwapLong(this, baseOffset, cmp, val);
  }

  /** CASes the busy field from 0 to 1 to acquire lock. */
  final boolean casBusy() {
    return UNSAFE.compareAndSwapInt(this, busyOffset, 0, 1);
  }

  /**
   * Computes the function of current and new value. Subclasses should open-code this update

  Striped64() {}

  /** CASes the base field. */
  final boolean casBase(long cmp, long val) {
    return UNSAFE.compareAndSwapLong(this, baseOffset, cmp, val);
  }

  /** CASes the busy field from 0 to 1 to acquire lock. */
  final boolean casBusy() {
    return UNSAFE.compareAndSwapInt(this, busyOffset, 0, 1);
  }

  /**
   * Computes the function of current and new value. Subclasses should open-code this update

  Striped64() {}

  /** CASes the base field. */
  final boolean casBase(long cmp, long val) {
    return UNSAFE.compareAndSwapLong(this, baseOffset, cmp, val);
  }

  /** CASes the busy field from 0 to 1 to acquire lock. */
  final boolean casBusy() {
    return UNSAFE.compareAndSwapInt(this, busyOffset, 0, 1);
  }

  /**
   * Computes the function of current and new value. Subclasses should open-code this update

  }

  // retainAll(empty)

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_emptyPreviouslyEmpty() {
    expectReturnsFalse(empty);
    expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_emptyPreviouslyEmptyUnsupported() {

  @ListFeature.Require(SUPPORTS_ADD_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAllAtIndex_supportedAllPresent() {
    assertTrue(
        "addAll(n, allPresent) should return true",
        getList().addAll(0, MinimalCollection.of(e0())));
    expectAdded(0, e0());
  }

  @ListFeature.Require(absent = SUPPORTS_ADD_WITH_INDEX)

    }
  }

  @CollectionSize.Require(SEVERAL)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemoveAllIgnoresCount() {
    initThreeCopies();
    assertTrue(getMultiset().removeAll(Collections.singleton(e0())));
    assertEmpty(getMultiset());
  }

  @CollectionSize.Require(SEVERAL)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRetainAllIgnoresCount() {

    expectMissing(e3(), e4());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutAll_supportedSomePresent() {
    putAll(MinimalCollection.of(e3(), e0()));
    expectAdded(e3());
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_PUT})
  @CollectionSize.Require(absent = ZERO)

  }

  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemoveIf_allPresent() {
    assertTrue("removeIf(x -> true) should return true", collection.removeIf(x -> true));
    expectContents();
  }

  @CollectionFeature.Require({SUPPORTS_ITERATOR_REMOVE, FAILS_FAST_ON_CONCURRENT_MODIFICATION})
  @CollectionSize.Require(SEVERAL)

public class CollectionAddAllTester<E extends @Nullable Object>
    extends AbstractCollectionTester<E> {
  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_supportedNothing() {
    assertFalse("addAll(nothing) should return false", collection.addAll(emptyCollection()));
    expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  public void testAddAll_unsupportedNothing() {
    try {
      assertFalse(