* subclass below. That's because the Entry might be non-terminal in the key bucket but terminal
     * in the value bucket (or vice versa).
     */
    private final transient @Nullable ImmutableMapEntry<K, V> nextInKeyBucket;

    NonTerminalImmutableMapEntry(
        K key, V value, @Nullable ImmutableMapEntry<K, V> nextInKeyBucket) {
      super(key, value);

 */
@GwtCompatible
abstract class AbstractBiMap<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingMap<K, V> implements BiMap<K, V>, Serializable {

  private transient Map<K, V> delegate;

  @RetainedWith private transient AbstractBiMap<V, K> inverse;

  /** Package-private constructor for creating a map-backed bimap. */
  AbstractBiMap(Map<K, V> forward, Map<V, K> backward) {

      firstNode.nextSibling = null;
      this.count = 1;
    }
  }

  private transient @Nullable Node<K, V> head; // the head for all keys
  private transient @Nullable Node<K, V> tail; // the tail for all keys
  private transient Map<K, KeyList<K, V>> keyToKeyList;
  private transient int size;

  /*
   * Tracks modifications to keyToKeyList so that addition or removal of keys invalidates

 *
 * @author James Sexton
 */
final class MapRetrievalCache<K, V> extends MapIteratorCache<K, V> {
  // See the note about volatile in the superclass.
  private transient volatile @Nullable CacheEntry<K, V> cacheEntry1;
  private transient volatile @Nullable CacheEntry<K, V> cacheEntry2;

  MapRetrievalCache(Map<K, V> backingMap) {
    super(backingMap);
  }

 */
package org.apache.maven.settings;

import java.io.Serializable;

import static java.util.Objects.requireNonNull;

public abstract class BaseObject implements Serializable, Cloneable {
    protected transient ChildrenTracking childrenTracking;

    protected Object delegate;

    public BaseObject() {}

    public BaseObject(Object delegate, BaseObject parent) {

package org.apache.maven.model;

import java.io.Serializable;

import static java.util.Objects.requireNonNull;

public abstract class BaseObject implements Serializable, Cloneable, InputLocationTracker {
    protected transient ChildrenTracking childrenTracking;

    protected Object delegate;

    public BaseObject() {}

    public BaseObject(Object delegate, BaseObject parent) {

        protected String id;

        protected Long version;

        protected Long seqNo;

        protected Long primaryTerm;

        private transient RequestOptionCall<IndexRequestBuilder> indexOption;

        private transient RequestOptionCall<DeleteRequestBuilder> deleteOption;

        public DocMeta id(String id) {
            this.id = id;
            myuniqueByProperty("_id");

    return Multisets.retainAllImpl(this, elementsToRetain);
  }

  @Override
  public abstract void clear();

  // Views

  @LazyInit private transient @Nullable Set<E> elementSet;

  @Override
  public Set<E> elementSet() {
    Set<E> result = elementSet;
    if (result == null) {
      elementSet = result = createElementSet();
    }
    return result;

package org.apache.maven.artifact.repository.metadata;

import java.io.Serializable;

import static java.util.Objects.requireNonNull;

public abstract class BaseObject implements Serializable, Cloneable {
    protected transient ChildrenTracking childrenTracking;

    protected Object delegate;

    public BaseObject() {}

    public BaseObject(Object delegate, BaseObject parent) {

 * delegation to save code size.
 *
 * @author Hayward Chan
 */
final class ForwardingImmutableCollection<E> extends ImmutableCollection<E> {

  final transient Collection<E> delegate;

  ForwardingImmutableCollection(Collection<E> delegate) {
    this.delegate = delegate;
  }

  @Override
  public UnmodifiableIterator<E> iterator() {