// implements Queue

    @Override
    public boolean offer(ReferenceEntry<K, V> entry) {
      // unlink
      connectAccessOrder(entry.getPreviousInAccessQueue(), entry.getNextInAccessQueue());

      // add to tail
      connectAccessOrder(head.getPreviousInAccessQueue(), entry);
      connectAccessOrder(entry, head);

      return true;
    }

    @CheckForNull
    @Override

    // implements Queue

    @Override
    public boolean offer(ReferenceEntry<K, V> entry) {
      // unlink
      connectAccessOrder(entry.getPreviousInAccessQueue(), entry.getNextInAccessQueue());

      // add to tail
      connectAccessOrder(head.getPreviousInAccessQueue(), entry);
      connectAccessOrder(entry, head);

      return true;
    }

    @CheckForNull
    @Override

      this.nextAccess = next;
    }

    private ReferenceEntry<K, V> previousAccess = nullEntry();

    @Override
    public ReferenceEntry<K, V> getPreviousInAccessQueue() {
      return previousAccess;
    }

    @Override
    public void setPreviousInAccessQueue(ReferenceEntry<K, V> previous) {
      this.previousAccess = previous;
    }

      this.nextAccess = next;
    }

    private ReferenceEntry<K, V> previousAccess = nullEntry();

    @Override
    public ReferenceEntry<K, V> getPreviousInAccessQueue() {
      return previousAccess;
    }

    @Override
    public void setPreviousInAccessQueue(ReferenceEntry<K, V> previous) {
      this.previousAccess = previous;
    }