@GwtIncompatible // SerializableTester
  public void testKeySetIsSerializable_jdkBackedImmutableMap() {
    class NonSerializableClass {}

    Entry<String, NonSerializableClass>[] entries =
        arrayOf(ImmutableMap.entryOf("one", new NonSerializableClass()));

    ImmutableMap<String, NonSerializableClass> map =
        JdkBackedImmutableMap.create(1, entries, /* throwIfDuplicateKeys= */ true);

      return emptyListIterator();
    }
    return new ArrayItr<>(array, position);
  }

  private static final class ArrayItr<T extends @Nullable Object>
      extends AbstractIndexedListIterator<T> {
    static final UnmodifiableListIterator<Object> EMPTY = new ArrayItr<>(new Object[0], 0);

    private final T[] array;