@Override
    public boolean hasPrevious() {
      return !previousElements.isEmpty();
    }

    @Override
    public E next() {
      return transferElement(nextElements, previousElements);
    }

    @Override
    public int nextIndex() {
      return previousElements.size();
    }

    @Override
    public E previous() {
      return transferElement(previousElements, nextElements);
    }

    this.reference = reference;
  }

  @Override
  public boolean isPresent() {
    return true;
  }

  @Override
  public T get() {
    return reference;
  }

  @Override
  public T or(T defaultValue) {
    checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
    return reference;
  }

  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {

    @Override
    String normalizeWord(String word) {
      return firstCharOnlyToUpper(word);
    }

    @Override
    String normalizeFirstWord(String word) {
      return Ascii.toLowerCase(word);
    }
  },

  /** Java and C++ class naming convention, e.g., "UpperCamel". */
  UPPER_CAMEL(CharMatcher.inRange('A', 'Z'), "") {
    @Override
    String normalizeWord(String word) {

      }
      return -1;
    }

    @Override
    ImmutableSortedSet<C> createDescendingSet() {
      return new DescendingImmutableSortedSet<>(this);
    }

    @Override
    boolean isPartialView() {
      return ranges.isPartialView();
    }

    @Override
    public String toString() {
      return ranges.toString();
    }

    @Override
    @J2ktIncompatible // serialization

    @Override
    public String getProjectName() {
        return null;
    }

    @Override
    public String getProjectPrefix() {
        return null;
    }

    @Override
    public String getGenerationGapBasePrefix() {
        return null;
    }

    @Override
    public DBDef getCurrentDBDef() {
        return null;
    }

  }

  @Override
  public Spliterator<E> spliterator() {
    return Spliterators.spliterator(elements, SPLITERATOR_CHARACTERISTICS);
  }

  @Override
  Object[] internalArray() {
    return elements;
  }

  @Override
  int internalArrayStart() {
    return 0;
  }

  @Override
  int internalArrayEnd() {
    return elements.length;
  }

  @Override

 */
abstract class AbstractHasher implements Hasher {
  @Override
  @CanIgnoreReturnValue
  public final Hasher putBoolean(boolean b) {
    return putByte(b ? (byte) 1 : (byte) 0);
  }

  @Override
  @CanIgnoreReturnValue
  public final Hasher putDouble(double d) {
    return putLong(Double.doubleToRawLongBits(d));
  }

  @Override
  @CanIgnoreReturnValue
  public final Hasher putFloat(float f) {

  /**
   * @since 11.0
   */
  @Override
  public void put(K key, V value) {
    throw new UnsupportedOperationException();
  }

  /**
   * @since 12.0
   */
  @Override
  public void putAll(Map<? extends K, ? extends V> m) {
    for (Entry<? extends K, ? extends V> entry : m.entrySet()) {
      put(entry.getKey(), entry.getValue());
    }
  }

  @Override
  public void cleanUp() {}

  @Override

  }

  @Override
  public String toString() {
    return serviceName() + " [" + state() + "]";
  }

  @Override
  public final boolean isRunning() {
    return delegate.isRunning();
  }

  @Override
  public final State state() {
    return delegate.state();
  }

  /**
   * @since 13.0
   */
  @Override

  }

  @Override
  public void write(byte[] b, int off, int len) throws IOException {
    // Override slow FilterOutputStream impl
    out.write(b, off, len);
  }

  @Override
  public void writeBoolean(boolean v) throws IOException {
    ((DataOutputStream) out).writeBoolean(v);
  }

  @Override
  public void writeByte(int v) throws IOException {