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));
  }

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

        .containsExactly(immutableEntry("foo", 1), immutableEntry("quux", 3))
        .inOrder();
  }

  public void testInsertionOrderAfterRemoveLast() {
    BiMap<String, Integer> map = HashBiMap.create();
    map.put("foo", 1);
    map.put("bar", 2);
    map.put("quux", 3);

    map.remove("quux");
    assertThat(map.entrySet())
        .containsExactly(immutableEntry("foo", 1), immutableEntry("bar", 2))

        .containsExactly(immutableEntry("foo", 1), immutableEntry("quux", 3))
        .inOrder();
  }

  public void testInsertionOrderAfterRemoveLast() {
    BiMap<String, Integer> map = HashBiMap.create();
    map.put("foo", 1);
    map.put("bar", 2);
    map.put("quux", 3);

    map.remove("quux");
    assertThat(map.entrySet())
        .containsExactly(immutableEntry("foo", 1), immutableEntry("bar", 2))

        new Builder<String, Integer>().put(immutableEntry("one", 1)).build();
    assertEquals(asList(1), multimap.get("one"));
  }

  public void testBuilder_withImmutableEntryAndNullContents() {
    Builder<String, Integer> builder = new Builder<>();
    assertThrows(
        NullPointerException.class, () -> builder.put(immutableEntry("one", (Integer) null)));

    @Override
    public SampleElements<Entry<Country, String>> samples() {
      return new SampleElements<>(
          immutableEntry(Country.CANADA, "DOLLAR"),
          immutableEntry(Country.CHILE, "PESO"),
          immutableEntry(Country.UK, "POUND"),
          immutableEntry(Country.JAPAN, "YEN"),
          immutableEntry(Country.SWITZERLAND, "FRANC"));
    }

    @SuppressWarnings("unchecked")
    @Override

            Maps.<@Nullable String, Integer>immutableEntry(null, 7),
            Maps.<@Nullable String, Integer>immutableEntry(null, 3),
            Maps.<@Nullable String, Integer>immutableEntry(null, 1),
            Maps.<String, @Nullable Integer>immutableEntry("tree", null),
            immutableEntry("tree", 0),
            immutableEntry("google", 6),
            immutableEntry("google", 2))
        .inOrder();
  }

      assertEquals(ImmutableSet.of(key1, key2), cache.asMap().keySet());
      assertThat(cache.asMap().values()).containsExactly(value1, value2);
      assertEquals(
          ImmutableSet.of(immutableEntry(key1, value1), immutableEntry(key2, value2)),
          cache.asMap().entrySet());
    }
  }

  public void testInvalidate() {
    for (LoadingCache<Key, String> cache : caches()) {
      Key key1 = new Key(1);

    public SampleElements<Entry<Class, Impl>> samples() {
      return new SampleElements<>(
          immutableEntry((Class) One.class, new Impl(1)),
          immutableEntry((Class) Two.class, new Impl(2)),
          immutableEntry((Class) Three.class, new Impl(3)),
          immutableEntry((Class) Four.class, new Impl(4)),
          immutableEntry((Class) Five.class, new Impl(5)));
    }

    @Override
    @SuppressWarnings("unchecked")

    forwarding.put("b", 2);
    assertEquals(immutableEntry("b", 2), forwarding.lastEntry());
    forwarding.put("c", 3);
    assertEquals(immutableEntry("c", 3), forwarding.lastEntry());
    forwarding.put("a", 1);
    assertEquals(immutableEntry("c", 3), forwarding.lastEntry());
    forwarding.remove("c");
    assertEquals(immutableEntry("b", 2), forwarding.lastEntry());
  }