return (result == null) ? keySet = createKeySet() : result;
  }

  /*
   * This could have a good default implementation of return new ImmutableKeySet<K, V>(this),
   * but ProGuard can't figure out how to eliminate that default when RegularImmutableMap
   * overrides it.
   */
  abstract ImmutableSet<K> createKeySet();

  UnmodifiableIterator<K> keyIterator() {

        if (extensionRecord == null) {
            ClassRealm extensionRealm = classRealmManager.createExtensionRealm(plugin, toAetherArtifacts(artifacts));

            // TODO figure out how to use the same PluginDescriptor when running mojos

            PluginDescriptor pluginDescriptor = null;
            if (plugin.isExtensions() && !artifacts.isEmpty()) {

                     pass -XepCompilingTestOnlyCode, and that argument needs to
                     be passed as part of the same <arg> as -Xplugin:ErrorProne,
                     and I gave up trying to figure out how to do that for test
                     compilation only. -->
                <arg>-Xplugin:ErrorProne -Xep:NullArgumentForNonNullParameter:OFF -Xep:Java8ApiChecker:ERROR</arg>

	objQuorum int // Number of disks needed for an object to 'exist'.

	// An optimization request only an 'n' amount of versions from xl.meta
	// to avoid resolving all versions to figure out the latest 'version'
	// for ListObjects, ListObjectsV2
	requestedVersions int

	bucket string // Name of the bucket. Used for generating cached fileinfo.

	}

	if dir == "" {
		if !dirSet {
			return nil, fmt.Errorf("missing option must be provided")
		}
		return nil, fmt.Errorf("provided option cannot be empty")
	}

	// Disallow relative paths, figure out absolute paths.
	dirAbs, err := filepath.Abs(dir)
	if err != nil {
		return nil, err
	}
	err = mkdirAllIgnorePerm(dirAbs)
	if err != nil {

      // We're looking for the smallest charsPerChunk such that bitsPerChar * charsPerChunk is a
      // multiple of 8. A multiple of 8 has 3 low zero bits, so we just need to figure out how many
      // extra zero bits we need to add to the end of bitsPerChar to get 3 in total.
      // The logic here would be wrong for bitsPerChar > 8, but since we require distinct ASCII

			}
		}
	} // Success.
	return nil
}

func getValidPath(path string) (string, error) {
	if path == "" {
		return path, errInvalidArgument
	}

	var err error
	// Disallow relative paths, figure out absolute paths.
	path, err = filepath.Abs(path)
	if err != nil {
		return path, err
	}

	fi, err := Lstat(path)
	if err != nil && !osIsNotExist(err) {
		return path, err
	}

    assertEquals("b", consumingIterator.next());
    assertThat(list).isEmpty();

    assertFalse(consumingIterator.hasNext());
  }

  @GwtIncompatible // ?
  // TODO: Figure out why this is failing in GWT.
  public void testConsumingIterable_duelingIterators() {
    // Test data
    List<String> list = Lists.newArrayList(asList("a", "b"));

    // Test & Verify

    assertEquals("b", consumingIterator.next());
    assertThat(list).isEmpty();

    assertFalse(consumingIterator.hasNext());
  }

  @GwtIncompatible // ?
  // TODO: Figure out why this is failing in GWT.
  public void testConsumingIterable_duelingIterators() {
    // Test data
    List<String> list = Lists.newArrayList(asList("a", "b"));

    // Test & Verify

    return (UnmodifiableListIterator<T>) ArrayItr.EMPTY;
  }

  /**
   * This is an enum singleton rather than an anonymous class so ProGuard can figure out it's only
   * referenced by emptyModifiableIterator().
   */
  private enum EmptyModifiableIterator implements Iterator<Object> {
    INSTANCE;

    @Override
    public boolean hasNext() {