if (value != null) {
      return value;
    }

    // Store a local reference to the cache entry. If the backing map is immutable, this,
    // in combination with immutable cache entries, will ensure a thread-safe cache.
    CacheEntry<K, V> entry;

    // Check cache. We use == on purpose because it's cheaper and a cache miss is ok.
    entry = cacheEntry1;
    if (entry != null && entry.key == key) {
      return entry.value;

   * The entry was manually removed by the user. This can result from the user invoking {@link
   * Cache#invalidate}, {@link Cache#invalidateAll(Iterable)}, {@link Cache#invalidateAll()}, {@link
   * Map#remove}, {@link ConcurrentMap#remove}, or {@link Iterator#remove}.
   */
  EXPLICIT {
    @Override
    boolean wasEvicted() {
      return false;
    }
  },

  /**

   * The entry was manually removed by the user. This can result from the user invoking {@link
   * Cache#invalidate}, {@link Cache#invalidateAll(Iterable)}, {@link Cache#invalidateAll()}, {@link
   * Map#remove}, {@link ConcurrentMap#remove}, or {@link Iterator#remove}.
   */
  EXPLICIT {
    @Override
    boolean wasEvicted() {
      return false;
    }
  },

  /**

                 * be cached and cause other types to fail even though they may
                 * not be the authority for the name. For example, if a WINS lookup
                 * for FOO fails and caches unknownAddress for FOO, a subsequent
                 * lookup for FOO using BCAST should not fail because of that
                 * name cached from WINS.
                 *

          + ")";
    }
  }

  /**
   * Returns a supplier that caches the instance supplied by the delegate and removes the cached
   * value after the specified time has passed. Subsequent calls to {@code get()} return the cached
   * value if the expiration time has not passed. After the expiration time, a new value is
   * retrieved, cached, and returned. See: <a
   * href="http://en.wikipedia.org/wiki/Memoization">memoization</a>

    private static final Logger logger = LogManager.getLogger(PopularWordHelper.class);

    /** Character used to separate cache key components */
    protected static final char CACHE_KEY_SPLITTER = '\n';

    /** Cache for storing popular word lists */
    protected Cache<String, List<String>> cache;

    /** Fess configuration instance */
    protected FessConfig fessConfig;

    /**
     * Default constructor.
     */

    when {
      name.equals("Cache-Control", ignoreCase = true) -> {
        if (headerValue != null) {
          // Multiple cache-control headers means we can't use the raw value.
          canUseHeaderValue = false
        } else {
          headerValue = value
        }
      }
      name.equals("Pragma", ignoreCase = true) -> {
        // Might specify additional cache-control params. We invalidate just in case.

        String directoryPath = smbFile.getPath();

        // Check if we can use cached directory listing
        if (dirManager.canCacheDirectoryListing(directoryPath)) {
            List<SmbFile> cachedFiles = dirManager.getCachedDirectoryListing(directoryPath);
            if (cachedFiles != null) {
                log.debug("Using cached directory listing for: {}", directoryPath);

    /** The request attribute key for storing cached user agent type */
    protected static final String USER_AGENT_TYPE = "ViewHelper.UserAgent";

    /**
     * Determines the user agent type from the current HTTP request.
     * The method analyzes the User-Agent header to categorize the browser type
     * and caches the result in the request attribute for subsequent calls.
     *

        // Should not throw any exception.
        assertDoesNotThrow(() -> dfsImpl.cache(mockContext, "invalidpath", mockReferral));
    }

    @Test
    void testCache_ValidPath() {
        // Scenario: A valid referral is cached.
        DfsReferralDataInternal mockReferral = mock(DfsReferralDataInternal.class);