}

  @LazyInit private transient @Nullable Reference<Multiset<N>> predecessorsReference;

  @Override
  public Set<N> predecessors() {
    return Collections.unmodifiableSet(predecessorsMultiset().elementSet());
  }

  private Multiset<N> predecessorsMultiset() {
    Multiset<N> predecessors = getReference(predecessorsReference);
    if (predecessors == null) {
      predecessors = HashMultiset.create(inEdgeMap.values());

  }

  @LazyInit private transient @Nullable Reference<Multiset<N>> predecessorsReference;

  @Override
  public Set<N> predecessors() {
    return Collections.unmodifiableSet(predecessorsMultiset().elementSet());
  }

  private Multiset<N> predecessorsMultiset() {
    Multiset<N> predecessors = getReference(predecessorsReference);
    if (predecessors == null) {
      predecessors = HashMultiset.create(inEdgeMap.values());

  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemove_occurrences_absent() {
    int distinct = getMultiset().elementSet().size();
    assertEquals("multiset.remove(absent, 0) didn't return 0", 0, getMultiset().remove(e3(), 2));
    assertEquals(distinct, getMultiset().elementSet().size());
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  public void testRemove_occurrences_unsupported_absent() {

  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemove_occurrences_absent() {
    int distinct = getMultiset().elementSet().size();
    assertEquals("multiset.remove(absent, 0) didn't return 0", 0, getMultiset().remove(e3(), 2));
    assertEquals(distinct, getMultiset().elementSet().size());
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  public void testRemove_occurrences_unsupported_absent() {

      return JdkBackedImmutableMultiset.create(entries);
    }
  }

  @Override
  public int count(@Nullable Object element) {
    throw new AssertionError();
  }

  @Override
  public ImmutableSet<E> elementSet() {
    throw new AssertionError();
  }

  @Override
  Entry<E> getEntry(int index) {
    throw new AssertionError();
  }

  @Override
  boolean isPartialView() {
    throw new AssertionError();

      }
      return JdkBackedImmutableMultiset.create(contents.entrySet());
    }
  }

  static final class ElementSet<E> extends ImmutableSet.Indexed<E> {
    private final List<Entry<E>> entries;
    // TODO(cpovirk): @Weak?
    private final Multiset<E> delegate;

    ElementSet(List<Entry<E>> entries, Multiset<E> delegate) {
      this.entries = entries;
      this.delegate = delegate;
    }

    assertContainsAllOf(
        keys.entrySet(), Multisets.immutableEntry((K) null, 2), Multisets.immutableEntry(k1(), 1));
  }

  public void testKeysElementSet() {
    assertEquals(multimap().keySet(), multimap().keys().elementSet());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testKeysRemove() {
    int original = multimap().keys().remove(k0(), 1);
    assertEquals(max(original - 1, 0), multimap().get(k0()).size());
  }

        @Override
        Iterator<Entry<E>> entryIterator() {
          return backingMultiset.descendingMultiset().entrySet().iterator();
        }
      };
    }

    @Override
    public NavigableSet<E> elementSet() {
      return new StandardElementSet();
    }

    @Override
    public Entry<E> firstEntry() {
      return standardFirstEntry();
    }

    @Override
    public Entry<E> lastEntry() {

    assertEquals(expected, SerializableTester.reserialize(expected));
  }

  @CollectionFeature.Require(SERIALIZABLE_INCLUDING_VIEWS)
  public void testElementSetSerialization() {
    Set<E> expected = getMultiset().elementSet();
    assertEquals(expected, SerializableTester.reserialize(expected));
  }

    assertEquals(expected, SerializableTester.reserialize(expected));
  }

  @CollectionFeature.Require(SERIALIZABLE_INCLUDING_VIEWS)
  public void testElementSetSerialization() {
    Set<E> expected = getMultiset().elementSet();
    assertEquals(expected, SerializableTester.reserialize(expected));
  }