return null;
        }).when(smbTree).close();

        smbTree.close();

        verify(smbTree).close();
    }

    /**
     * Test for unwrap preserving type safety.
     * Verifies that unwrap maintains type safety at compile time.
     */
    @Test
    void testUnwrap_typeSafety() {
        CustomSmbTree customTree = mock(CustomSmbTree.class);

        // Null-safety: return null for blank templates
        // Early return is safe here as no resources have been allocated yet
        if (StringUtil.isBlank(template)) {
            if (logger.isDebugEnabled()) {
                logger.debug("Template is blank, returning null");
            }
            return null;
        }

        // Null-safety: use empty map if paramMap is null

import java.util.Map;

/**
 * {@link HashMap} with an upper limit on the number of entries. When a new entry is added, the oldest entry is discarded using LRU if the limit is exceeded.
 * <p>
 * <strong>Thread-Safety:</strong> This class is <strong>NOT thread-safe</strong>.
 * It extends {@link LinkedHashMap} without synchronization. If multiple threads access
 * an instance concurrently, and at least one thread modifies the map structurally,

import org.dbflute.utflute.core.PlainTestCase;

/**
 * Test class for {@link Handler} and its inner class {@link Handler.GcsURLConnection}.
 * This test covers URL parsing, connection state management, and thread-safety.
 */
public class HandlerTest extends PlainTestCase {
    @Override
    protected void setUp() throws Exception {
        super.setUp();
        new StandardCrawlerContainer();
    }

    /**

                                                key="labels.user_street"/></label>
                                        <div class="col-sm-9">
                                            <la:errors property="attributes.street"/>

 *   <li>{@link DataService} - The service for managing access results.</li>
 * </ul>
 *
 * <p>Each parameter is stored in a ThreadLocal variable to ensure thread safety.</p>
 *
 * <p>Usage example:</p>
 * <pre>
 * {@code
 * UrlQueue<?> urlQueue = CrawlingParameterUtil.getUrlQueue();
 * CrawlingParameterUtil.setUrlQueue(newUrlQueue);
 *

| Packages | lowercase | `org.codelibs.fess.suggest` |

### JavaDoc Requirements

All public classes and methods require JavaDoc with `@param`, `@return`, and `@throws` tags.

### Best Practices

**Null Safety:**
```java
public Suggester(final Client client, final SuggestSettings settings) {
    this.client = Objects.requireNonNull(client, "client must not be null");

- **Authentication**: NTLM, Kerberos, SPNEGO unified subsystem
- **SLF4J Logging**: Comprehensive logging throughout the codebase
- **Resource Management**: AutoCloseable patterns for file handles and connections
- **Thread Safety**: Components support concurrent access
- **DFS Support**: Distributed File System resolution
- **Streaming Operations**: Efficient directory listings and file operations
- **Buffer Caching**: Optimized buffer management

            BufferCache.releaseBuffer(correctBuffer); // Should accept correct size
        });
    }

    /**
     * Test concurrent buffer allocation and release for thread safety.
     */
    @Test
    public void testConcurrentBufferOperations() throws Exception {
        // Given
        int threadCount = 10;
        int opsPerThread = 100;

**Template Method**: `AbstractCrawlerClient`, `AbstractExtractor` - common logic with overrides
**DI**: LastaFlute container with `@Resource` and XML config

### Core Principles

**Thread Safety**:
- `AtomicLong` for counters (`CrawlerContext.accessCount`)
- `volatile` for status flags
- Synchronized blocks for critical sections
- Thread-local storage via `CrawlingParameterUtil`

**Resource Management**: