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, "")
		}

    @DisplayName("writeWireFormat should write header and trailer")
    void testWriteWireFormat() {
        packet.type = SessionServicePacket.SESSION_MESSAGE;
        packet.trailerLength = 10; // Mock trailer will write 10 bytes

        byte[] dst = new byte[50];
        int totalWritten = packet.writeWireFormat(dst, 0);

        assertEquals(14, totalWritten); // 4 header + 10 trailer

		return FormatUnknown
	}

	// Guess the magic values.
	magic := string(b.toUSTAR().magic())
	version := string(b.toUSTAR().version())
	trailer := string(b.toSTAR().trailer())
	switch {
	case magic == magicUSTAR && trailer == trailerSTAR:
		return formatSTAR
	case magic == magicUSTAR:
		return FormatUSTAR | FormatPAX
	case magic == magicGNU && version == versionGNU:
		return FormatGNU

   * Timing-Allow-Origin}</a> header field name.
   *
   * @since 15.0
   */
  public static final String TIMING_ALLOW_ORIGIN = "Timing-Allow-Origin";

  /** The HTTP {@code Trailer} header field name. */
  public static final String TRAILER = "Trailer";

  /** The HTTP {@code Transfer-Encoding} header field name. */
  public static final String TRANSFER_ENCODING = "Transfer-Encoding";

pkg math/rand, type Source64 interface, Seed(int64)
pkg math/rand, type Source64 interface, Uint64() uint64
pkg net/http, const TrailerPrefix ideal-string
pkg net/http, const TrailerPrefix = "Trailer:"
pkg net/http/httptrace, type ClientTrace struct, TLSHandshakeDone func(tls.ConnectionState, error)
pkg net/http/httptrace, type ClientTrace struct, TLSHandshakeStart func()

	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.
//

// then this returns an error.
func (tw *Writer) Close() error {
	if tw.err == ErrWriteAfterClose {
		return nil
	}
	if tw.err != nil {
		return tw.err
	}

	// Trailer: two zero blocks.
	err := tw.Flush()
	for i := 0; i < 2 && err == nil; i++ {
		_, err = tw.w.Write(zeroBlock[:])
	}

	// Ensure all future actions are invalid.
	tw.err = ErrWriteAfterClose

 *
 * <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. */

    public fun headers(headers: Headers): Builder =
      apply {
        this.headers_ = headers.newBuilder()
      }

    /** Sets the trailers and returns this. */
    public fun trailers(trailers: Headers): Builder =
      apply {
        this.trailers_ = trailers.newBuilder()
      }

    /** Don't trust the client during the SSL handshake. */
    public fun failHandshake(): Builder =
      apply {