CacheTesting.warmUp(cache, 0, 10);
    Set<Integer> keySet = cache.asMap().keySet();
    assertThat(keySet).containsExactly(0, 1, 2, 3, 4, 5, 6, 7, 8, 9);

    // re-order
    getAll(cache, asList(0, 1, 2));
    CacheTesting.drainRecencyQueues(cache);
    assertThat(keySet).containsExactly(3, 4, 5, 6, 7, 8, 9, 0, 1, 2);

    // evict 3, 4, 5
    getAll(cache, asList(10, 11, 12));

    for (int i = 0; i < 10; i++) {
      cache.getUnchecked(i);
      ticker.advance(1, MILLISECONDS);
    }
    Set<Integer> keySet = cache.asMap().keySet();
    assertThat(keySet).containsExactly(0, 1, 2, 3, 4, 5, 6, 7, 8, 9);

    // 0 expires
    ticker.advance(1, MILLISECONDS);
    assertThat(keySet).containsExactly(1, 2, 3, 4, 5, 6, 7, 8, 9);

    // reorder
    getAll(cache, asList(0, 1, 2));

      return delegate;
    }

    @Override
    public Set<K> keySet() {
      return new ForwardingSet<K>() {
        @Override
        protected Set<K> delegate() {
          return delegate.keySet();
        }

        @Override
        public Iterator<K> iterator() {
          return Iterators.unmodifiableIterator(delegate.keySet().iterator());
        }

        @Override

        data.putValue("key2", "value2");
        data.putValue("key3", "value3");

        Set<String> keySet = data.getKeySet();
        assertNotNull(keySet);
        assertEquals(3, keySet.size());
        assertTrue(keySet.contains("key1"));
        assertTrue(keySet.contains("key2"));
        assertTrue(keySet.contains("key3"));
    }

    public void test_getKeySetEmpty() {
        // Test getKeySet on empty metadata

    SortedSet<@Nullable String> keySet = multimap.keySet();

    assertEquals(null, keySet.first());
    assertEquals("google", keySet.last());
    assertEquals(StringLength.COMPARATOR, keySet.comparator());
    assertEquals(Sets.<@Nullable String>newHashSet(null, "tree"), keySet.headSet("yahoo"));
    assertEquals(newHashSet("google"), keySet.tailSet("yahoo"));

  protected final void assertInvariants(Map<K, V> map) {
    Set<K> keySet = map.keySet();
    Collection<V> valueCollection = map.values();
    Set<Entry<K, V>> entrySet = map.entrySet();

    assertEquals(map.size() == 0, map.isEmpty());
    assertEquals(map.size(), keySet.size());
    assertEquals(keySet.size() == 0, keySet.isEmpty());
    assertEquals(!keySet.isEmpty(), keySet.iterator().hasNext());

    int expectedKeySetHash = 0;

  protected final void assertInvariants(Map<K, V> map) {
    Set<K> keySet = map.keySet();
    Collection<V> valueCollection = map.values();
    Set<Entry<K, V>> entrySet = map.entrySet();

    assertEquals(map.size() == 0, map.isEmpty());
    assertEquals(map.size(), keySet.size());
    assertEquals(keySet.size() == 0, keySet.isEmpty());
    assertEquals(!keySet.isEmpty(), keySet.iterator().hasNext());

    int expectedKeySetHash = 0;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import java.io.Serializable;
import org.jspecify.annotations.Nullable;

/**
 * {@code keySet()} implementation for {@link ImmutableMap}.
 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 */
@GwtCompatible
final class ImmutableMapKeySet<K, V> extends IndexedImmutableSet<K> {

    EnumBiMap<Currency, Country> bimap = EnumBiMap.create(map);

    Iterator<Currency> iter = bimap.keySet().iterator();
    assertEquals(Currency.DOLLAR, iter.next());
    iter.remove();

    // forward map ordered by currency
    assertThat(bimap.keySet()).containsExactly(Currency.FRANC, Currency.PESO).inOrder();
    // forward map ordered by currency (even for country values)

    builder.put("c", 4);
    builder.put("a", 2);
    builder.put("b", 6);
    ImmutableListMultimap<String, Integer> multimap = builder.build();
    assertThat(multimap.keySet()).containsExactly("d", "c", "b", "a").inOrder();
    assertThat(multimap.values()).containsExactly(2, 4, 3, 6, 5, 2).inOrder();
    assertThat(multimap.get("a")).containsExactly(5, 2).inOrder();