final CountDownLatch getStartedSignal = new CountDownLatch(2);
    final CountDownLatch letGetFinishSignal = new CountDownLatch(1);
    final CountDownLatch getFinishedSignal = new CountDownLatch(2);
    final String getKey = "get";
    final String refreshKey = "refresh";
    final String suffix = "Suffix";

    CacheLoader<String, String> computeFunction =

    @DoNotCall
    @Deprecated
    @Override
    public final ImmutableSortedMap<K, V> buildKeepingLast() {
      // TODO(emcmanus): implement
      throw new UnsupportedOperationException(
          "ImmutableSortedMap.Builder does not yet implement buildKeepingLast()");
    }
  }

  private final transient RegularImmutableSortedSet<K> keySet;
  private final transient ImmutableList<V> valueList;

@ElementTypesAreNonnullByDefault
public class SetsTest extends TestCase {

  private static final IteratorTester.KnownOrder KNOWN_ORDER =
      IteratorTester.KnownOrder.KNOWN_ORDER;

  private static final Collection<Integer> EMPTY_COLLECTION = Arrays.<Integer>asList();

  private static final Collection<Integer> SOME_COLLECTION = Arrays.asList(0, 1, 1);

  private static final Iterable<Integer> SOME_ITERABLE =
      new Iterable<Integer>() {

  private static final class PickyIterable<E> implements Iterable<E> {
    final List<E> elements;
    int modCount = 0;

    PickyIterable(E... elements) {
      this.elements = new ArrayList<E>(asList(elements));
    }

    @Override
    public Iterator<E> iterator() {
      return new PickyIterator();
    }

    final class PickyIterator implements Iterator<E> {

 * Preconditions}</a>.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Preconditions {
  private Preconditions() {}

  private interface Impossible {}

  /**
   * Ensures the truth of an expression involving one or more parameters to the calling method.
   *

   */
  @SuppressWarnings({"sunapi", "removal"}) // b/318391980
  private static final class UnsafeAtomicHelper extends AtomicHelper {
    static final sun.misc.Unsafe UNSAFE;
    static final long LISTENERS_OFFSET;
    static final long WAITERS_OFFSET;
    static final long VALUE_OFFSET;
    static final long WAITER_THREAD_OFFSET;
    static final long WAITER_NEXT_OFFSET;

    static {
      sun.misc.Unsafe unsafe = null;

    final CountDownLatch getStartedSignal = new CountDownLatch(2);
    final CountDownLatch letGetFinishSignal = new CountDownLatch(1);
    final CountDownLatch getFinishedSignal = new CountDownLatch(2);
    final String getKey = "get";
    final String refreshKey = "refresh";
    final String suffix = "Suffix";

    CacheLoader<String, String> computeFunction =

 * anyway, so we just need to get by without the annotations here until Kotlin better understands
 * our other nullness annotations.
 */
final class Synchronized {
  private Synchronized() {}

  static class SynchronizedObject implements Serializable {
    final Object delegate;
    final Object mutex;

    SynchronizedObject(Object delegate, @CheckForNull Object mutex) {
      this.delegate = checkNotNull(delegate);

    @DoNotCall
    @Deprecated
    @Override
    public final ImmutableSortedMap<K, V> buildKeepingLast() {
      // TODO(emcmanus): implement
      throw new UnsupportedOperationException(
          "ImmutableSortedMap.Builder does not yet implement buildKeepingLast()");
    }
  }

  private final transient RegularImmutableSortedSet<K> keySet;
  private final transient ImmutableList<V> valueList;

  public void testNullPointerExceptions() {
    new NullPointerTester().testAllPublicStaticMethods(Maps.class);
  }

  private static final Map<Integer, Integer> EMPTY = Collections.emptyMap();
  private static final Map<Integer, Integer> SINGLETON = Collections.singletonMap(1, 2);

  public void testMapDifferenceEmptyEmpty() {
    MapDifference<Integer, Integer> diff = Maps.difference(EMPTY, EMPTY);