assertTrue("Listener called before it was expected", expectCall);
      assertFalse("Listener called more than once", wasCalled());
      called.set(true);
    }

    public void expectCall() {
      assertFalse("expectCall is already true", expectCall);
      expectCall = true;
    }

    public boolean wasCalled() {
      return called.get();
    }
  }

      assertTrue("Listener called before it was expected", expectCall);
      assertFalse("Listener called more than once", wasCalled());
      called.set(true);
    }

    public void expectCall() {
      assertFalse("expectCall is already true", expectCall);
      expectCall = true;
    }

    public boolean wasCalled() {
      return called.get();
    }
  }

  // expiration

  /** Returns true if the entry has expired. */
  boolean isExpired(ReferenceEntry<K, V> entry, long now) {
    checkNotNull(entry);
    if (expiresAfterAccess() && (now - entry.getAccessTime() >= expireAfterAccessNanos)) {
      return true;
    }
    if (expiresAfterWrite() && (now - entry.getWriteTime() >= expireAfterWriteNanos)) {
      return true;
    }
    return false;
  }

   *
   * @param mayInterruptIfRunning {@code true} if the thread executing this task should be
   *     interrupted; otherwise, in-progress tasks are allowed to complete, but the step will be
   *     cancelled regardless
   * @return {@code false} if the step could not be cancelled, typically because it has already
   *     completed normally; {@code true} otherwise
   */
  @CanIgnoreReturnValue

   *
   * @param mayInterruptIfRunning {@code true} if the thread executing this task should be
   *     interrupted; otherwise, in-progress tasks are allowed to complete, but the step will be
   *     cancelled regardless
   * @return {@code false} if the step could not be cancelled, typically because it has already
   *     completed normally; {@code true} otherwise
   */
  @CanIgnoreReturnValue

    @Override
    public NavigableMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
      return subMap(fromKey, true, toKey, false);
    }

    @Override
    public NavigableMap<K, V2> tailMap(@ParametricNullness K fromKey) {
      return tailMap(fromKey, true);
    }

    @Override
    public NavigableMap<K, V2> tailMap(@ParametricNullness K fromKey, boolean inclusive) {

    @Override
    public NavigableMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
      return subMap(fromKey, true, toKey, false);
    }

    @Override
    public NavigableMap<K, V2> tailMap(@ParametricNullness K fromKey) {
      return tailMap(fromKey, true);
    }

    @Override
    public NavigableMap<K, V2> tailMap(@ParametricNullness K fromKey, boolean inclusive) {

  // expiration

  /** Returns true if the entry has expired. */
  boolean isExpired(ReferenceEntry<K, V> entry, long now) {
    checkNotNull(entry);
    if (expiresAfterAccess() && (now - entry.getAccessTime() >= expireAfterAccessNanos)) {
      return true;
    }
    if (expiresAfterWrite() && (now - entry.getWriteTime() >= expireAfterWriteNanos)) {
      return true;
    }
    return false;
  }