* partially collected.
   */
  @Nullable ReferenceEntry<K, V> getEntry(@Nullable Object key) {
    // does not impact recency ordering
    if (key == null) {
      return null;
    }
    int hash = hash(key);
    return segmentFor(hash).getEntry(key, hash);
  }

  void refresh(K key) {
    int hash = hash(checkNotNull(key));

   * collected. Does not impact recency ordering.
   */
  @Nullable E getEntry(@Nullable Object key) {
    if (key == null) {
      return null;
    }
    int hash = hash(key);
    return segmentFor(hash).getEntry(key, hash);
  }

  @Override
  public boolean containsKey(@Nullable Object key) {
    if (key == null) {
      return false;

   * partially collected.
   */
  @Nullable ReferenceEntry<K, V> getEntry(@Nullable Object key) {
    // does not impact recency ordering
    if (key == null) {
      return null;
    }
    int hash = hash(key);
    return segmentFor(hash).getEntry(key, hash);
  }

  void refresh(K key) {
    int hash = hash(checkNotNull(key));

   * collected. Does not impact recency ordering.
   */
  @Nullable E getEntry(@Nullable Object key) {
    if (key == null) {
      return null;
    }
    int hash = hash(key);
    return segmentFor(hash).getEntry(key, hash);
  }

  @Override
  public boolean containsKey(@Nullable Object key) {
    if (key == null) {
      return false;

 *
 *   final long seqNum;
 *   final E entry;
 *
 *   public FIFOEntry(E entry) {
 *     seqNum = seq.getAndIncrement();
 *     this.entry = entry;
 *   }
 *
 *   public E getEntry() {
 *     return entry;
 *   }
 *
 *   public int compareTo(FIFOEntry<E> other) {
 *     int res = entry.compareTo(other.entry);
 *     if (res == 0 && other.entry != this.entry) {