class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
    extends CompactHashMap<K, V> {
  // TODO(lowasser): implement removeEldestEntry so this can be used as a drop-in replacement

  /** Creates an empty {@code CompactLinkedHashMap} instance. */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      CompactLinkedHashMap<K, V> create() {
    return new CompactLinkedHashMap<>();
  }

  /**

 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class MoreCollectorsTest extends TestCase {
  public void testToOptionalEmpty() {
    assertThat(Stream.empty().collect(MoreCollectors.toOptional())).isEmpty();
  }

  public void testToOptionalSingleton() {
    assertThat(Stream.of(1).collect(MoreCollectors.toOptional())).hasValue(1);
  }

  public void testToOptionalNull() {

public final class HashMultiset<E extends @Nullable Object> extends AbstractMapBasedMultiset<E> {

  /** Creates a new, empty {@code HashMultiset} using the default initial capacity. */
  public static <E extends @Nullable Object> HashMultiset<E> create() {
    return create(ObjectCountHashMap.DEFAULT_SIZE);
  }

  /**
   * Creates a new, empty {@code HashMultiset} with the specified expected number of distinct
   * elements.
   *

  // Default from ArrayList
  private static final int DEFAULT_VALUES_PER_KEY = 3;

  @VisibleForTesting transient int expectedValuesPerKey;

  /**
   * Creates a new, empty {@code ArrayListMultimap} with the default initial capacities.
   *
   * <p>This method will soon be deprecated in favor of {@code
   * MultimapBuilder.hashKeys().arrayListValues().build()}.
   */

  /**
   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
   */
  @SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
    return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
  }

  /**

  }

  public void testEmptiesFirst() {
    Optional<String> empty = Optional.empty();
    Optional<String> abc = Optional.of("abc");
    Optional<String> z = Optional.of("z");

    Comparator<Optional<String>> comparator = Comparators.emptiesFirst(comparing(String::length));
    Helpers.testComparator(comparator, empty, z, abc);

    // Just demonstrate that no explicit type parameter is required

  }

  @GwtIncompatible // ObjectArrays.newArray(Class, int)
  public void testNewArray_fromClass_Empty() {
    String[] empty = ObjectArrays.newArray(String.class, 0);
    assertEquals(String[].class, empty.getClass());
    assertThat(empty).isEmpty();
  }

  @GwtIncompatible // ObjectArrays.newArray(Class, int)
  public void testNewArray_fromClass_Nonempty() {

  }

  @GwtIncompatible // ObjectArrays.newArray(Class, int)
  public void testNewArray_fromClass_Empty() {
    String[] empty = ObjectArrays.newArray(String.class, 0);
    assertEquals(String[].class, empty.getClass());
    assertThat(empty).isEmpty();
  }

  @GwtIncompatible // ObjectArrays.newArray(Class, int)
  public void testNewArray_fromClass_Nonempty() {

@SuppressWarnings({"serial", "rawtypes"})
@ElementTypesAreNonnullByDefault
final class RegularImmutableSortedSet<E> extends ImmutableSortedSet<E> {
  static final RegularImmutableSortedSet<Comparable> NATURAL_EMPTY_SET =
      new RegularImmutableSortedSet<>(ImmutableList.<Comparable>of(), Ordering.natural());

  @VisibleForTesting final transient ImmutableList<E> elements;

   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.
   */
  @SuppressWarnings("unchecked")
  public static <T> Collector<T, ?, Optional<T>> toOptional() {
    return (Collector) TO_OPTIONAL;
  }