import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.logging.Level;
import org.jspecify.annotations.Nullable;

/**
 * A helper which does some thread-safe operations for aggregate futures, which must be implemented
 * differently in GWT. Namely:
 *
 * <ul>
 *   <li>Lazily initializes a set of seen exceptions
 *   <li>Decrements a counter atomically
 * </ul>
 */
@GwtCompatible

**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**:

            return entryIterator.hasNext();
          }

          @Override
          public K next() {
            Entry<K, V> entry = entryIterator.next(); // store local reference for thread-safety
            cacheEntry = entry;
            return entry.getKey();
          }
        };
      }

      @Override
      public int size() {
        return backingMap.size();
      }

        // 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

If one or more drives are offline at the start of a PutObject or NewMultipartUpload operation the object will have additional data
protection bits added automatically to provide the regular safety for these objects up to 50% of the number of drives.
This will allow normal write operations to take place on systems that exceed the write tolerance.

- **Bean introspection** - The comprehensive `BeanDesc` system provides metadata about JavaBeans, accessed through `BeanDescFactory.getBeanDesc(Class)`
- **Type safety** - Extensive use of generics and null-safe operations throughout the API
- **Resource management** - Proper handling of resources with utilities like `CloseableUtil` and `DisposableUtil`

### Key Architectural Patterns

- **Cross-Language Compatibility:**
Java serialization is inherently Java-centric and does not support cross-language scenarios well.

- **Type Safety:**
Java serialization does not enforce type safety as strictly as some alternatives, potentially leading to runtime errors.

## Decision

We do not use Java serialization.

 * <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,
 * it must be synchronized externally.
 * </p>
 * <p>
 * For thread-safe usage, wrap with {@link java.util.Collections#synchronizedMap(Map)}:
 * </p>

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();
    }

    /**

 *   <li>Handle project forking states</li>
 * </ul>
 *
 * The service maintains the mutable state of projects as they progress through
 * their build lifecycle, ensuring thread-safety and proper state management.
 * All implementations must be thread-safe as they may be accessed concurrently
 * during parallel builds.
 *
 * @since 4.0.0
 * @see org.apache.maven.api.services.ProjectBuilder
 * @see Project
 */
@Experimental