* in {@linkplain WeakReference weak} references.
 *
 * <p>Usage example:
 *
 * {@snippet :
 * ConcurrentMap<Request, Stopwatch> timers = new MapMaker()
 *     .concurrencyLevel(4)
 *     .weakKeys()
 *     .makeMap();
 * }
 *
 * <p>These features are all optional; {@code new MapMaker().makeMap()} returns a valid concurrent
 * map that behaves similarly to a {@link ConcurrentHashMap}.
 *

    testAddAndRemove(new ConcurrentSkipListMap<String, AtomicInteger>());
  }

  public void testAddAndRemove_mapMakerMap() throws Exception {
    MapMaker mapMaker = new MapMaker();
    // force MapMaker to use its own MapMakerInternalMap
    mapMaker.useCustomMap = true;
    testAddAndRemove(mapMaker.<String, AtomicInteger>makeMap());
  }

  private void testAddAndRemove(ConcurrentMap<String, AtomicInteger> map)

   * anywhere else
   */

  public void testInitialCapacity_negative() {
    MapMaker maker = new MapMaker();
    assertThrows(IllegalArgumentException.class, () -> maker.initialCapacity(-1));
  }

  // TODO(cpovirk): enable when ready (apparently after a change to our GWT emulation)
  public void xtestInitialCapacity_setTwice() {
    MapMaker maker = new MapMaker().initialCapacity(16);
    try {
      // even to the same value is not allowed

  @JsType(isNative = true, name = "Array", namespace = JsPackage.GLOBAL)
  private interface NativeArray {
    @JsProperty
    void setLength(int length);
  }

  static MapMaker tryWeakKeys(MapMaker mapMaker) {
    return mapMaker;
  }

  static <E extends Enum<E>> Class<E> getDeclaringClassOrObjectForJ2cl(E e) {
    Class<E> classOrNull = getDeclaringClassOrNullForJ2cl(e);
    @SuppressWarnings("unchecked")

   * GWT). This is sometimes acceptable, when only server-side code could generate enough volume
   * 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();
  }

   * GWT). This is sometimes acceptable, when only server-side code could generate enough volume
   * 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();
  }

    MapMakerStrongKeysStrongValues {
      @Override
      public <K extends Comparable<K>, V> Map<K, V> create(Map<K, V> map) {
        // We use a "custom" equivalence to force MapMaker to make a MapMakerInternalMap.
        ConcurrentMap<K, V> newMap = new MapMaker().keyEquivalence(Equivalence.equals()).makeMap();
        checkState(newMap instanceof MapMakerInternalMap);
        newMap.putAll(map);
        return newMap;
      }
    },

    @J2ktIncompatible // java.io.ObjectInputStream
    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
      in.defaultReadObject();
      MapMaker mapMaker = readMapMaker(in);
      delegate = mapMaker.makeMap();
      readEntries(in);
    }

    private Object readResolve() {
      return delegate;
    }
  }

     */
    final Map<LockGraphNode, ExampleStackTrace> allowedPriorLocks =
        new MapMaker().weakKeys().makeMap();

    /**
     * The map tracking lock nodes that can cause a lock acquisition cycle if acquired before this
     * node.
     */
    final Map<LockGraphNode, PotentialDeadlockException> disallowedPriorLocks =
        new MapMaker().weakKeys().makeMap();

    final String lockName;

       * 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 =