/**
 * An immutable {@code Map.Entry}, used both by {@link
 * com.google.common.collect.Maps#immutableEntry(Object, Object)} and by other parts of {@code
 * common.collect} as a superclass.
 */
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
class ImmutableEntry<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapEntry<K, V> implements Serializable {

/**
 * An immutable {@code Map.Entry}, used both by {@link
 * com.google.common.collect.Maps#immutableEntry(Object, Object)} and by other parts of {@code
 * common.collect} as a superclass.
 */
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
class ImmutableEntry<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapEntry<K, V> implements Serializable {

      int bucket = Hashing.smear(hash) & mask;
      ImmutableEntry<E> bucketHead = hashTable[bucket];
      ImmutableEntry<E> newEntry;
      if (bucketHead == null) {
        boolean canReuseEntry =
            entry instanceof ImmutableEntry && !(entry instanceof NonTerminalEntry);
        newEntry =
            canReuseEntry ? (ImmutableEntry<E>) entry : new ImmutableEntry<E>(element, count);
      } else {

    assertEquals(1, keys.count(k1()));
    assertEquals(3, keys.size());
    assertContainsAllOf(keys, k0(), k1());
    assertContainsAllOf(
        keys.entrySet(), Multisets.immutableEntry(k0(), 2), Multisets.immutableEntry(k1(), 1));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testKeysCountAbsentNullKey() {
    assertEquals(0, multimap().keys().count(null));
  }

    getMultiset()
        .forEachEntry((element, count) -> actual.add(Multisets.immutableEntry(element, count)));
    assertEquals(expected, actual);
  }

  public void testForEachEntryDuplicates() {
    initThreeCopies();
    List<Entry<E>> expected = Collections.singletonList(Multisets.immutableEntry(e0(), 3));
    List<Entry<E>> actual = new ArrayList<>();
    getMultiset()

    map.put("foo", 1);
    map.put("bar", 2);
    map.put("quux", 3);
    assertThat(map.entrySet())
        .containsExactly(
            Maps.immutableEntry("foo", 1),
            Maps.immutableEntry("bar", 2),
            Maps.immutableEntry("quux", 3))
        .inOrder();
  }

  public void testInsertionOrderAfterRemoveFirst() {
    BiMap<String, Integer> map = HashBiMap.create();

    assertEquals(1, keys.count(k1()));
    assertEquals(3, keys.size());
    assertContainsAllOf(keys, k0(), k1());
    assertContainsAllOf(
        keys.entrySet(), Multisets.immutableEntry(k0(), 2), Multisets.immutableEntry(k1(), 1));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testKeysCountAbsentNullKey() {
    assertEquals(0, multimap().keys().count(null));
  }

    assertTrue(map.entrySet().contains(immutableEntry(TypeToken.of(Integer.class), null)));
    assertNull(map.get(TypeToken.of(Integer.class)));
    assertNull(map.getInstance(Integer.class));

    map.putInstance(Long.class, null);
    assertTrue(map.containsKey(TypeToken.of(Long.class)));
    assertTrue(map.entrySet().contains(immutableEntry(TypeToken.of(Long.class), null)));

  @CheckForNull
  public Entry<E> pollFirstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    if (entryIterator.hasNext()) {
      Entry<E> result = entryIterator.next();
      result = Multisets.immutableEntry(result.getElement(), result.getCount());
      entryIterator.remove();
      return result;
    }
    return null;
  }

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {

  @CheckForNull
  public Entry<E> pollFirstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    if (entryIterator.hasNext()) {
      Entry<E> result = entryIterator.next();
      result = Multisets.immutableEntry(result.getElement(), result.getCount());
      entryIterator.remove();
      return result;
    }
    return null;
  }

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {