if (parent == null) {
      /*
       * The given directory is a filesystem root. All zero of its ancestors exist. This doesn't
       * mean that the root itself exists -- consider x:\ on a Windows machine without such a drive
       * -- or even that the caller can create it, but this method makes no such guarantees even for
       * non-root files.
       */
      return;
    }
    parent.mkdirs();

      listOf(
        Header(Header.TARGET_METHOD, "GET"),
        Header(Header.TARGET_SCHEME, "https"),
        Header(Header.TARGET_AUTHORITY, "squareup.com"),
        Header(Header.TARGET_PATH, "/cached"),
      )
    peer.sendFrame().pushPromise(3, 2, expectedRequestHeaders)
    val expectedResponseHeaders =
      listOf(
        Header(Header.RESPONSE_STATUS, "200"),
      )

    executeSynchronously("/", "Cache-Control", "only-if-cached")
      .assertCode(504)
      .assertBody("")
      .assertNoNetworkResponse()
      .assertNoCacheResponse()
  }

  @Test
  fun networkDropsOnConditionalGet() {
    client =
      client
        .newBuilder()
        .cache(cache)
        .build()

    // Seed the cache.
    server.enqueue(

        // Previously determined to be an unsafe lock acquisition.
        // Create a new PotentialDeadlockException with the same causal chain
        // (the example cycle) as that of the cached exception.
        PotentialDeadlockException exception =
            new PotentialDeadlockException(
                acquiredLock, this, previousDeadlockException.getConflictingStackTrace());

   * ImmutableMapValues<K, V>(this)}, but ProGuard can't figure out how to eliminate that default
   * when RegularImmutableMap overrides it.
   */
  abstract ImmutableCollection<V> createValues();

  // cached so that this.multimapView().inverse() only computes inverse once
  @LazyInit private transient @Nullable ImmutableSetMultimap<K, V> multimapView;

  /**
   * Returns a multimap view of the map.
   *

	if !s.checkID(params.DiskID) {
		return grid.NewRemoteErr(errDiskNotFound)
	}
	if params.Cache == nil {
		return grid.NewRemoteErrString("NSScannerHandler: provided cache is nil")
	}

	// Collect updates, stream them before the full cache is sent.
	updates := make(chan dataUsageEntry, 1)
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()

	// Create indicates that the lister should not attempt to load an existing cache.
	Create bool

	// Include pure directories.
	IncludeDirectories bool

	// Transient is set if the cache is transient due to an error or being a reserved bucket.
	// This means the cache metadata will not be persisted on disk.
	// A transient result will never be returned from the cache so knowing the list id is required.
	Transient bool

        // Improved attribute caching with more granular cache validation
        long currentTime = System.currentTimeMillis();
        if (this.attrExpiration > currentTime) {
            log.trace("Using cached attributes (expires in {}ms)", this.attrExpiration - currentTime);
            return this.isExists;
        }

        // Fast path for already resolved existence with recent cache

			if err == nil {
				cache.Info.replication = replicationConfig{
					Config:  rcfg,
					remotes: tgts,
				}
			}
		}
	}

	// Check if bucket is object locked.
	lr, err := globalBucketObjectLockSys.Get(cache.Info.Name)
	if err != nil {
		scannerLogOnceIf(ctx, err, cache.Info.Name)
		return cache, err
	}

	vcfg, _ := globalBucketVersioningSys.Get(cache.Info.Name)

   * ImmutableMapValues<K, V>(this)}, but ProGuard can't figure out how to eliminate that default
   * when RegularImmutableMap overrides it.
   */
  abstract ImmutableCollection<V> createValues();

  // cached so that this.multimapView().inverse() only computes inverse once
  @LazyInit private transient @Nullable ImmutableSetMultimap<K, V> multimapView;

  /**
   * Returns a multimap view of the map.
   *