() -> CacheBuilder.newBuilder().maximumSize(1).weigher(constantWeigher(42)));
  }

  @GwtIncompatible // weakKeys
  public void testKeyStrengthSetTwice() {
    CacheBuilder<Object, Object> builder1 = CacheBuilder.newBuilder().weakKeys();
    assertThrows(IllegalStateException.class, () -> builder1.weakKeys());
  }

  @GwtIncompatible // weakValues
  public void testValueStrengthSetTwice() {

  /** Returns an iterable containing all combinations weakKeys and weak/softValues. */
  private static Iterable<CacheBuilder<Object, Object>> allKeyValueStrengthMakers() {
    return ImmutableList.of(
        createCacheBuilder(),
        createCacheBuilder().weakValues(),
        createCacheBuilder().softValues(),
        createCacheBuilder().weakKeys(),
        createCacheBuilder().weakKeys().weakValues(),

  /** Returns an iterable containing all combinations weakKeys and weak/softValues. */
  private static Iterable<CacheBuilder<Object, Object>> allKeyValueStrengthMakers() {
    return ImmutableList.of(
        createCacheBuilder(),
        createCacheBuilder().weakValues(),
        createCacheBuilder().softValues(),
        createCacheBuilder().weakKeys(),
        createCacheBuilder().weakKeys().weakValues(),

        ConcurrentMap<K, V> newMap = new MapMaker().weakKeys().makeMap();
        checkState(newMap instanceof MapMakerInternalMap);
        newMap.putAll(map);
        return newMap;
      }
    },
    MapMakerWeakKeysWeakValues {
      @Override
      public <K extends Comparable<K>, V> Map<K, V> create(Map<K, V> map) {
        ConcurrentMap<K, V> newMap = new MapMaker().weakKeys().weakValues().makeMap();

  private static Iterable<MapMaker> allWeakKeyStrengthMakers() {
    return ImmutableList.of(createMapMaker().weakKeys(), createMapMaker().weakKeys().weakValues());
  }

  private static Iterable<MapMaker> allWeakValueStrengthMakers() {
    return ImmutableList.of(
        createMapMaker().weakValues(), createMapMaker().weakKeys().weakValues());
  }

  public void testNullParameters() throws Exception {

  private static Iterable<MapMaker> allWeakKeyStrengthMakers() {
    return ImmutableList.of(createMapMaker().weakKeys(), createMapMaker().weakKeys().weakValues());
  }

  private static Iterable<MapMaker> allWeakValueStrengthMakers() {
    return ImmutableList.of(
        createMapMaker().weakValues(), createMapMaker().weakKeys().weakValues());
  }

  public void testNullParameters() throws Exception {

      this.mapMaker.concurrencyLevel(concurrencyLevel);
      return this;
    }

    public <E> Interner<E> build() {
      if (!strong) {
        mapMaker.weakKeys();
      }
      return new InternerImpl<>(mapMaker);
    }
  }

  /** Returns a fresh {@link InternerBuilder} instance. */
  public static InternerBuilder newBuilder() {
    return new InternerBuilder();
  }

       * UnsignedBytesBenchmark. TODO(cpovirk): benchmark this
       */
      /*
       * A CopyOnWriteArraySet<WeakReference> is faster than a newSetFromMap of a MapMaker map with
       * weakKeys() and concurrencyLevel(1), even up to at least 12 cached exception types.
       */
      private static final Set<WeakReference<Class<? extends Exception>>> validClasses =
          new CopyOnWriteArraySet<>();

      this.mapMaker.concurrencyLevel(concurrencyLevel);
      return this;
    }

    public <E> Interner<E> build() {
      if (!strong) {
        mapMaker.weakKeys();
      }
      return new InternerImpl<>(mapMaker);
    }
  }

  /** Returns a fresh {@link InternerBuilder} instance. */
  public static InternerBuilder newBuilder() {
    return new InternerBuilder();
  }

   * that reclamation becomes important.
   */
  @J2ktIncompatible
  static MapMaker tryWeakKeys(MapMaker mapMaker) {
    return mapMaker.weakKeys();
  }

  static <E extends Enum<E>> Class<E> getDeclaringClassOrObjectForJ2cl(E e) {
    return e.getDeclaringClass();
  }

  static int reduceIterationsIfGwt(int iterations) {
    return iterations;