func newSignV4ChunkedReader(req *http.Request, trailer bool) (io.ReadCloser, APIErrorCode) {
	cred, seedSignature, region, seedDate, errCode := calculateSeedSignature(req, trailer)
	if errCode != ErrNone {
		return nil, errCode
	}

	if trailer {
		// Discard anything unsigned.
		req.Trailer = make(http.Header)
		trailers := req.Header.Values(awsTrailerHeader)
		for _, key := range trailers {
			req.Trailer.Add(key, "")
		}

	return r.Header.Get(xhttp.AmzContentSha256) == streamingContentSHA256Trailer &&
		r.Method == http.MethodPut
}

// Verify if the request has AWS Streaming Signature Version '4', with unsigned content and trailer.
func isRequestUnsignedTrailerV4(r *http.Request) bool {
	return r.Header.Get(xhttp.AmzContentSha256) == unsignedPayloadTrailer &&
		r.Method == http.MethodPut
}

// Authorization type.
//

	req, err := http.NewRequest(http.MethodPut, getPutObjectURL(s.endPoint, bucketName, "test-cve-object.txt"), nil)
	c.Assert(err, nil)

	req.Body = io.NopCloser(bytes.NewReader([]byte("foobar!\n")))
	req.Trailer = http.Header{}
	req.Trailer.Set("x-amz-checksum-crc32", "rK0DXg==")

	now := UTCNow()

	req = signer.StreamingUnsignedV4(req, "", 8, now)

	maliciousHeaders := http.Header{

 *
 * <p>Example usage:
 * <pre>
 *   Crawler crawler = new Crawler();
 *   crawler.addUrl("http://example.com/");
 *   crawler.execute();
 *   crawler.close();
 * </pre>
 */
public class Crawler implements Runnable, AutoCloseable {

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

    /**
     * Service for managing URL queues during crawling.
     */

 * </pre>
 */
public class Crawler {

    /**
     * Creates a new instance of Crawler.
     */
    public Crawler() {
        // Default constructor
    }

    /** Logger instance for this class. */
    private static final Logger logger = LogManager.getLogger(Crawler.class);

    /** Thread name for web and file system crawling process. */

    <glob pattern="*.wspolicy"/>
  </mime-type>
  
  <mime-type type="image/x-tga">
     <alias type="image/x-targa"/>
     <!-- trailer bytes: 54 52 55 45 56 49 53 49 4F 4E 2D 58 46 49 4C 45 2E 00
          trailer as string: TRUEVISION-XFILE\\x2E\\x00
          Some .tga files may be conflicting with application/x-123 recognition, 

 */
package org.codelibs.fess.crawler;

import java.io.File;

import org.codelibs.core.io.ResourceUtil;
import org.codelibs.fess.crawler.container.CrawlerContainer;
import org.codelibs.fess.crawler.entity.UrlQueue;
import org.codelibs.fess.crawler.filter.impl.UrlFilterImpl;
import org.codelibs.fess.crawler.service.DataService;
import org.codelibs.fess.crawler.service.UrlQueueService;

});

Crawler crawler = container.getComponent("crawler");
crawler.addUrl("https://example.com");
crawler.crawlerContext.setMaxAccessCount(500);
String sessionId = crawler.execute();
```

### Background Crawling

```java
// Configure for background execution
crawler.setBackground(true);
String sessionId = crawler.execute();

// Check crawling status

      .build()

  @Test
  fun trailersHttp1() {
    trailers(Protocol.HTTP_1_1)
  }

  @Test
  fun trailersHttp2() {
    trailers(Protocol.HTTP_2)
  }

  private fun trailers(protocol: Protocol) {
    enableProtocol(protocol)

    server.enqueue(
      MockResponse
        .Builder()
        .addHeader("h1", "v1")
        .trailers(headersOf("t1", "v2"))
        .body(protocol, "Hello")

import org.codelibs.fess.crawler.filter.impl.UrlFilterImpl;
import org.codelibs.fess.crawler.service.DataService;
import org.codelibs.fess.crawler.service.UrlFilterService;
import org.codelibs.fess.crawler.service.UrlQueueService;
import org.codelibs.fess.crawler.transformer.impl.FileTransformer;
import org.codelibs.fess.crawler.util.CrawlerWebServer;
import org.codelibs.opensearch.runner.OpenSearchRunner;
import org.dbflute.utflute.lastadi.LastaDiTestCase;