public void testKeySetEntrySetValues() {
    for (LoadingCache<Key, String> cache : caches()) {
      Key key1 = new Key(1);
      String value1 = key1.toString();
      Key key2 = new Key(2);
      String value2 = key2.toString();
      assertSame(value1, cache.getUnchecked(key1));
      assertSame(value2, cache.getUnchecked(key2));
      assertEquals(ImmutableSet.of(key1, key2), cache.asMap().keySet());

  public void testKeySetEntrySetValues() {
    for (LoadingCache<Key, String> cache : caches()) {
      Key key1 = new Key(1);
      String value1 = key1.toString();
      Key key2 = new Key(2);
      String value2 = key2.toString();
      assertSame(value1, cache.getUnchecked(key1));
      assertSame(value2, cache.getUnchecked(key2));
      assertEquals(ImmutableSet.of(key1, key2), cache.asMap().keySet());

   *
   * @param keys the unique, non-null keys whose values should be loaded
   * @return a map from each key in {@code keys} to the value associated with that key; <b>may not
   *     contain null values</b>
   * @throws Exception if unable to load the result
   * @throws InterruptedException if this method is interrupted. {@code InterruptedException} is

   */
  @CanIgnoreReturnValue // TODO(b/27479612): consider removing this?
  V getUnchecked(K key);

  /**
   * Returns a map of the values associated with {@code keys}, creating or retrieving those values
   * if necessary. The returned map contains entries that were already cached, combined with newly
   * loaded entries; it will never contain null keys or values.
   *

  /** Discards any cached value for key {@code key}. */
  void invalidate(@CompatibleWith("K") Object key);

  /**
   * Discards any cached values for keys {@code keys}.
   *
   * @since 11.0
   */
  // For discussion of <? extends Object>, see getAllPresent.
  void invalidateAll(Iterable<? extends Object> keys);

  /** Discards all entries in the cache. */
  void invalidateAll();

  @CheckForNull
  public V forcePut(K key, @ParametricNullness V value) {
    return super.forcePut(key, value);
  }

  /** Returns the associated key type. */
  @GwtIncompatible
  public Class<K> keyType() {
    return keyTypeOrObjectUnderJ2cl;
  }

  /**
   * @serialData the key class, number of entries, first key, first value, second key, second value,
   *     and so on.
   */

 * Null row keys, columns keys, and values are not supported.
 *
 * <p>Lookups by row key are often faster than lookups by column key, because the data is stored in
 * a {@code Map<R, Map<C, V>>}. A method call like {@code column(columnKey).get(rowKey)} still runs
 * quickly, since the row key is provided. However, {@code column(columnKey).size()} takes longer,

      public Map<Object, Object> create(List<?> keys) {
        return ImmutableMap.copyOf(
            Lists.transform(keys, k -> Maps.immutableEntry(k, "dummy value")));
      }
    },
    BUILDER_PUT_ONE_BY_ONE {
      @Override
      public Map<Object, Object> create(List<?> keys) {
        ImmutableMap.Builder<Object, Object> builder = ImmutableMap.builder();
        for (Object k : keys) {
          builder.put(k, "dummy value");

    return delegate().getAll(keys);
  }

  @Override
  public V apply(K key) {
    return delegate().apply(key);
  }

  @Override
  public void refresh(K key) {
    delegate().refresh(key);
  }

  /**
   * A simplified version of {@link ForwardingLoadingCache} where subclasses can pass in an already
   * constructed {@link LoadingCache} as the delegate.

      return super.containsEntry(key, value);
    }

    @Override
    public Set<V> get(@Nullable K key) {
      assertTrue(Thread.holdsLock(mutex));
      /* TODO: verify that the Collection is also synchronized? */
      return super.get(key);
    }

    @Override
    public boolean put(K key, V value) {
      assertTrue(Thread.holdsLock(mutex));
      return super.put(key, value);
    }