/*
       * If another handleException() caller created the set, we need to use that copy in case yet
       * other callers have added to it.
       *
       * This read is guaranteed to get us the right value because we only set this once (here).
       *
       * requireNonNull is safe because either our compareAndSet succeeded or it failed because
       * another thread did it for us.
       */

    return delegate.isEmpty();
  }

  @Override
  public Object[] toArray() {
    return delegate.toArray();
  }

  @Override
  public <T extends @Nullable Object> T[] toArray(T[] other) {
    return delegate.toArray(other);
  }

  @Override
  public String toString() {
    return delegate.toString();
  }

  // TODO(cpovirk): equals(), as well, in case it's any faster than Sets.equalsImpl?

  @Override

remarking as it went, `One side will make you grow taller, and
the other side will make you grow shorter.'

  `One side of WHAT?  The other side of WHAT?' thought Alice to
herself.

  `Of the mushroom,' said the Caterpillar, just as if she had
asked it aloud; and in another moment it was out of sight.

  Alice remained looking thoughtfully at the mushroom for a

        "A Set should equal any other Set containing the same elements,"
            + " even if some elements are null.",
        getSet().equals(MinimalSet.from(elements)));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_otherContainsNull() {
    Collection<E> elements = getSampleElements(getNumElements() - 1);
    elements.add(null);
    Set<E> other = MinimalSet.from(elements);

        "A Set should equal any other Set containing the same elements,"
            + " even if some elements are null.",
        getSet().equals(MinimalSet.from(elements)));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_otherContainsNull() {
    Collection<E> elements = getSampleElements(getNumElements() - 1);
    elements.add(null);
    Set<E> other = MinimalSet.from(elements);

    return new EquivalenceTester<>(equivalence);
  }

  /**
   * Adds a group of objects that are supposed to be equivalent to each other and not equivalent to
   * objects in any other equivalence group added to this tester.
   */
  @CanIgnoreReturnValue
  public EquivalenceTester<T> addEquivalenceGroup(T first, T... rest) {
    addEquivalenceGroup(Lists.asList(first, rest));

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
    tests, either. This causes it to fail to find AtomicLongMapTest.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
    tests, either. This causes it to fail to find AtomicLongMapTest.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
    tests, either. This causes it to fail to find AtomicLongMapTest.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
    tests, either. This causes it to fail to find AtomicLongMapTest.