final Map<String, List<String>> headerFieldMap = file.getHeaderFields();
                if (headerFieldMap != null) {
                    for (final Map.Entry<String, List<String>> entry : headerFieldMap.entrySet()) {
                        responseData.addMetaData(entry.getKey(), entry.getValue());
                    }
                }

                if (file.canRead()) {

import org.apache.logging.log4j.Logger;
import org.codelibs.core.beans.util.BeanUtil;
import org.codelibs.fess.crawler.Constants;
import org.codelibs.fess.crawler.entity.AccessResultData;
import org.codelibs.fess.crawler.entity.ResponseData;
import org.codelibs.fess.crawler.entity.ResultData;
import org.codelibs.fess.crawler.exception.CrawlerSystemException;
import org.codelibs.fess.crawler.exception.CrawlingAccessException;

 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.crawler.util;

import org.codelibs.fess.crawler.CrawlerContext;
import org.codelibs.fess.crawler.entity.AccessResult;
import org.codelibs.fess.crawler.entity.UrlQueue;
import org.codelibs.fess.crawler.service.DataService;
import org.codelibs.fess.crawler.service.UrlQueueService;

/**

        final List<AccessResultImpl<Long>> acList = new ArrayList<>();
        for (final Map.Entry<String, Map<String, AccessResultImpl<Long>>> entry : sessionMap.entrySet()) {
            if (entry.getValue() != null) {
                final AccessResultImpl<Long> ar = entry.getValue().get(url);
                if (ar != null) {
                    acList.add(ar);
                }
            }

 */
package org.codelibs.fess.suggest.index.writer;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.codelibs.fess.suggest.entity.SuggestItem;
import org.codelibs.fess.suggest.settings.SuggestSettings;
import org.opensearch.index.query.QueryBuilder;
import org.opensearch.transport.client.Client;

/**
 * Interface for writing suggest items.
 */

│   └── service/             # Core services
├── fess-crawler-lasta/       # LastaFlute DI integration
└── fess-crawler-opensearch/  # OpenSearch backend
```

### Key Components

#### Core Engine
- **Crawler**: Main orchestrator managing crawl execution
- **CrawlerContext**: Execution context and configuration
- **CrawlerThread**: Individual crawler thread implementation

#### Client Architecture

import org.apache.logging.log4j.Logger;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.fess.crawler.Constants;
import org.codelibs.fess.crawler.entity.AccessResult;
import org.codelibs.fess.crawler.entity.OpenSearchUrlQueue;
import org.codelibs.fess.crawler.entity.UrlQueue;
import org.codelibs.fess.crawler.exception.OpenSearchAccessException;
import org.codelibs.fess.crawler.service.UrlQueueService;

	pad  int64      // Amount of padding to write after current file entry
	curr fileWriter // Writer for current file entry
	hdr  Header     // Shallow copy of Header that is safe for mutations
	blk  block      // Buffer to use as temporary local storage

	// err is a persistent error.
	// It is only the responsibility of every exported method of Writer to
	// ensure that this error is sticky.
	err error
}

            }

            lhaFile = new LhaFile(tempFile);
            @SuppressWarnings("unchecked")
            final Enumeration<LhaHeader> entries = lhaFile.entries();
            long contentSize = 0;
            while (entries.hasMoreElements()) {
                final LhaHeader head = entries.nextElement();
                contentSize += head.getOriginalSize();
                if (maxContentSize != -1 && contentSize > maxContentSize) {

import org.codelibs.fess.crawler.client.AbstractCrawlerClient;
import org.codelibs.fess.crawler.client.AccessTimeoutTarget;
import org.codelibs.fess.crawler.entity.RequestData;
import org.codelibs.fess.crawler.entity.ResponseData;
import org.codelibs.fess.crawler.exception.ChildUrlsException;
import org.codelibs.fess.crawler.exception.CrawlerSystemException;