}

  @Override
  public @Nullable Entry<K, V> floorEntry(K key) {
    return delegate.floorEntry(checkValid(key));
  }

  @Override
  public @Nullable K floorKey(K key) {
    return delegate.floorKey(checkValid(key));
  }

  @Override
  public @Nullable V get(Object key) {
    return delegate.get(checkValid(key));
  }

  @Override
  public SortedMap<K, V> headMap(K toKey) {

  }

  @Override
  public @Nullable Entry<K, V> floorEntry(K key) {
    return delegate.floorEntry(checkValid(key));
  }

  @Override
  public @Nullable K floorKey(K key) {
    return delegate.floorKey(checkValid(key));
  }

  @Override
  public @Nullable V get(Object key) {
    return delegate.get(checkValid(key));
  }

  @Override
  public SortedMap<K, V> headMap(K toKey) {

  @Override
  protected void assertGet(K key, V... values) {
    assertGet(key, Arrays.asList(values));
  }

  @Override
  protected void assertGet(K key, Collection<? extends V> values) {
    assertEqualInOrder(values, multimap().get(key));

    if (!values.isEmpty()) {
      assertEqualInOrder(values, multimap().asMap().get(key));
      assertFalse(multimap().isEmpty());
    } else {

    resetContainer();
  }

  protected void assertGet(K key, V... values) {
    assertGet(key, Arrays.asList(values));
  }

  protected void assertGet(K key, Collection<? extends V> values) {
    assertEqualIgnoringOrder(values, multimap().get(key));

    if (!values.isEmpty()) {
      assertEqualIgnoringOrder(values, multimap().asMap().get(key));
      assertFalse(multimap().isEmpty());
    } else {

  protected Entry<K, V> entry(K key, V value) {
    return Helpers.mapEntry(key, value);
  }

  @Override
  protected void expectContents(Collection<Entry<K, V>> expected) {
    // TODO: move this to invariant checks once the appropriate hook exists?
    super.expectContents(expected);
    for (Entry<K, V> entry : expected) {
      assertEquals(

        getMap()
            .merge(
                k3(),
                v3(),
                (oldV, newV) -> {
                  throw new AssertionFailedError(
                      "Should not call merge function if key was absent");
                }));
    expectAdded(e3());
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testMappedToNull() {

    public Builder() {}

    Builder(int initCapacity) {
      super(initCapacity);
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> put(K key, V value) {
      super.put(key, value);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
      super.put(entry);
      return this;

    @Override
    public Collection<UnhashableObject> create(UnhashableObject[] elements) {
      ImmutableMap.Builder<Integer, UnhashableObject> builder = ImmutableMap.builder();
      int key = 1;
      for (UnhashableObject value : elements) {
        builder.put(key++, value);
      }
      return builder.buildOrThrow().values();
    }
  }

  public static class ImmutableMapKeyListGenerator extends TestStringListGenerator {
    @Override

                      case 0:
                        map.incrementAndGet(key);
                        threadSum++;
                        break;
                      case 1:
                        map.decrementAndGet(key);
                        threadSum--;
                        break;
                      case 2:
                        map.addAndGet(key, delta);
                        threadSum += delta;

 * collections generated by {@code entries}, {@code keys}, and {@code values} iterate across the
 * keys according to the above key ordering, and for each key they iterate across the values
 * according to the value ordering.
 *
 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
 * existing key-value pair has no effect.
 *
 * <p>Null keys and values are permitted (provided, of course, that the respective comparators