* of SerializedForm whose readResolve() method returns objects of the subclass type.
   */
  @J2ktIncompatible // serialization
  Object writeReplace() {
    return new SerializedForm<>(this);
  }

  @J2ktIncompatible // java.io.ObjectInputStream
  private void readObject(ObjectInputStream stream) throws InvalidObjectException {

    /*
     * requireNonNull is not safe: Joiner.on(...).join(somethingThatContainsNull) will indeed throw.
     * However, Joiner.on(...).useForNull(...).join(somethingThatContainsNull) *is* safe -- because
     * it returns a subclass of Joiner that overrides this method to tolerate null inputs.
     *
     * Unfortunately, we don't distinguish between these two cases in our public API: Joiner.on(...)

    /*
     * requireNonNull is not safe: Joiner.on(...).join(somethingThatContainsNull) will indeed throw.
     * However, Joiner.on(...).useForNull(...).join(somethingThatContainsNull) *is* safe -- because
     * it returns a subclass of Joiner that overrides this method to tolerate null inputs.
     *
     * Unfortunately, we don't distinguish between these two cases in our public API: Joiner.on(...)

 *
 * <p>Subclasses are guaranteed that the life cycle methods ({@link #runOneIteration}, {@link
 * #startUp} and {@link #shutDown}) will never run concurrently. Notably, if any execution of {@link
 * #runOneIteration} takes longer than its schedule defines, then subsequent executions may start
 * late. Also, all life cycle methods are executed with a lock held, so subclasses can safely modify

       * more information, see the comments in that class.
       *
       * We already know that that's how it behaves, and subclasses of Converter can't change that
       * behavior. So there's no sense in making all subclass authors exclude the method from any
       * NullPointerTester tests that they have.
       */
      ignoredMembers.add(Converter.class.getMethod("apply", Object.class));

    }

    @Override
    public void forEach(Consumer<? super T> action) {
      iterable.forEach(action);
    }

    @SuppressWarnings("unchecked") // safe upcast, assuming no one has a crazy Spliterator subclass
    @Override
    public Spliterator<T> spliterator() {
      return (Spliterator<T>) iterable.spliterator();
    }

    @Override
    public String toString() {
      return iterable.toString();

    }
  }

  public <T> void testRejectTypeVariable_withOwnerType() {
    // Neither has subclass
    assertHasTypeVariable(new From<Integer>().new To<String>().type());
    assertHasTypeVariable(new From<T>().new To<String>().type());
    assertHasTypeVariable(new From<Integer>().new To<T>().type());

    // Owner is subclassed
    assertHasTypeVariable(new From<Integer>() {}.new To<String>().type());

    }
  }

  public <T> void testRejectTypeVariable_withOwnerType() {
    // Neither has subclass
    assertHasTypeVariable(new From<Integer>().new To<String>().type());
    assertHasTypeVariable(new From<T>().new To<String>().type());
    assertHasTypeVariable(new From<Integer>().new To<T>().type());

    // Owner is subclassed
    assertHasTypeVariable(new From<Integer>() {}.new To<String>().type());

    return (Segment<K, V, E, S>[]) new Segment<?, ?, ?, ?>[ssize];
  }

  // Inner Classes

  /**
   * Segments are specialized versions of hash tables. This subclass inherits from ReentrantLock
   * opportunistically, just to simplify some locking and avoid separate construction.
   */
  @SuppressWarnings("serial") // This class is never serialized.
  abstract static class Segment<

    for (ClassInfo info :
        ClassPath.from(GwtTestSuite.class.getClassLoader()).getTopLevelClasses()) {
      if (info.getName().endsWith("_gwt")) {
        Class<?> clazz = info.load();
        // TODO(cpovirk): why does asSubclass() throw? Is it something about ClassLoaders?
        @SuppressWarnings("unchecked")
        Class<? extends GWTTestCase> cast = (Class<? extends GWTTestCase>) clazz;
        suite.addTestSuite(cast);
      }
    }