firstException = expected;
    // Second time should also fail, with a cached causal chain.
    expected = assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    // The causal chain should be cached.
    assertSame(firstException.getCause(), expected.getCause());
    // lockA should work after lockB is released.

)

// metricsCache - cache for metrics.
//
// When serving metrics, this cache is passed to the MetricsLoaderFn.
//
// This cache is used for metrics that would result in network/storage calls.
type metricsCache struct {
	dataUsageInfo       *cachevalue.Cache[DataUsageInfo]
	esetHealthResult    *cachevalue.Cache[HealthResult]
	driveMetrics        *cachevalue.Cache[storageMetrics]

		if len(dui.BucketsUsage) > 0 {
			internalLogOnceIf(GlobalContext, fmt.Errorf("unable to retrieve usage information for bucket: %s, relying on older value cached in-memory: err(%v)", bucket, err), "bucket-usage-cache-"+bucket)
		} else {

        if (lookup == null) {
            return customLifecycles != null ? customLifecycles : new HashMap<>();
        }

        // Lifecycles cannot be cached as extensions might add custom lifecycles later in the execution.
        try {
            return registry != null

- ISO 639-1 language codes: `en`, `ja`, `de`, `fr`, `sv`, etc.
- With region when needed: `pt_BR`, `zh_CN`, `zh_TW`, `en_IE`

### Cache Behavior

- Language items are cached for 1 hour by `SystemHelper`
- Restart the application after adding new languages

### Auto-Generated Files

Never edit these files manually (marked with `@author FreeGen`):
- `FessLabels.java`
- `FessMessages.java`

    @DisplayName("Should register and manage file cache")
    void testFileCache() {
        String path = "/share/cached.txt";
        Smb2LeaseKey key = leaseManager.requestLease(path, Smb2LeaseState.SMB2_LEASE_FULL);

        // Register a mock file with cache
        leaseManager.registerFileCache(path, null); // Using null for simplicity in test

        // Handle lease break which should trigger cache operations

        }

        // Only cache if we haven't reached the limit - O(1) check
        if (queueSize.get() < MAX_BUFFERS) {
            if (bufferQueue.offer(buf)) { // O(1) operation
                queueSize.incrementAndGet();
            }
        }
        // If queue is full, let the buffer be garbage collected
    }

    /**
     * Get current cache statistics for monitoring

    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.
     */

    protected static final String CONTENT_DISPOSITION = "Content-Disposition";

    /** Cache key for highlighted cache content */
    protected static final String HL_CACHE = "hl_cache";

    /** Cache key for search queries */
    protected static final String QUERIES = "queries";

    /** Cache key for cache message */
    protected static final String CACHE_MSG = "cache_msg";

- **Utility Classes** - All core functionality exposed through static utility methods for easy access

### Performance Optimizations
- **Caching** - Bean descriptors and reflection metadata are cached for improved performance
- **Lazy initialization** - Resources and expensive operations are initialized only when needed