|| validSurrogatePairAt(b, b.length() - s - 1)) {
      s--;
    }
    return a.subSequence(a.length() - s, a.length()).toString();
  }

  /**
   * True when a valid surrogate pair starts at the given {@code index} in the given {@code string}.
   * Out-of-range indexes return false.
   */
  @VisibleForTesting
  static boolean validSurrogatePairAt(CharSequence string, int index) {

    private static final long serialVersionUID = 0;
  }

  /**
   * Creates a {@code HashCode} from a hexadecimal ({@code base 16}) encoded string. The string must
   * be at least 2 characters long, and contain only valid, lower-cased hexadecimal characters.
   *
   * <p>This method accepts the exact format generated by {@link #toString}. If you require more

	//
	// This flag should only be set if the user intends to encode a non-portable
	// ZIP file for a specific localized region. Otherwise, the Writer
	// automatically sets the ZIP format's UTF-8 flag for valid UTF-8 strings.
	NonUTF8 bool

	CreatorVersion uint16
	ReaderVersion  uint16
	Flags          uint16

	// Method is the compression method. If zero, Store is used.
	Method uint16

	if s3Err == ErrNone && retentionMode.Valid() {
		metadata[strings.ToLower(xhttp.AmzObjectLockMode)] = string(retentionMode)
		metadata[strings.ToLower(xhttp.AmzObjectLockRetainUntilDate)] = amztime.ISO8601Format(retentionDate.UTC())
	}
	if s3Err == ErrNone && legalHold.Status.Valid() {
		metadata[strings.ToLower(xhttp.AmzObjectLockLegalHold)] = string(legalHold.Status)
	}

 *   <li>useEPSVwithIPv4: Whether to use EPSV with IPv4.</li>
 *   <li>isImplicit: Whether to use implicit SSL/TLS encryption.</li>
 *   <li>trustManager: The trust manager to use for SSL/TLS connections ("all", "valid", or "none").</li>
 *   <li>enterLocalPassiveMode: Whether to enter local passive mode.</li>
 *   <li>ftpAuthentications: An array of {@link FtpAuthentication} objects for different FTP URLs.</li>
 * </ul>
 *
 * <p>

        }
    }

    @Nested
    @DisplayName("Header Decoding Tests")
    class HeaderDecodingTests {

        @Test
        @DisplayName("decode_header should successfully parse valid header")
        void testDecodeHeaderSuccess() throws NdrException {
            // Mock NdrBuffer methods for successful decoding
            when(mockBuffer.dec_ndr_small()).thenReturn(5)

        assertEquals(2, sis.read());
    }

    @Test
    @DisplayName("Reading with null array throws NullPointerException")
    void readNullArrayThrowsException() {
        // Create stream with valid message header and data
        byte[] data = new byte[] { 1 };
        InputStream in = new ByteArrayInputStream(concat(messageHeader(1), data));
        SocketInputStream sis = new SocketInputStream(in);

		expectedOffset int64
		expectedErr    error
	}{
		{0, 0, 0, nil},
		{1 * humanize.MiByte, 0, 1 * humanize.MiByte, nil},
		{1 + humanize.MiByte, 1, 0, nil},
		{2 + humanize.MiByte, 1, 1, nil},
		// Its valid for zero sized object.
		{-1, 0, -1, nil},
		// Max fffset is always (size - 1).
		{(1 + 2 + 4 + 5 + 7) + (5 * humanize.MiByte) - 1, 4, 1048582, nil},
		// Error if offset is size.

}

// Check to see if Policy is signed correctly.
func doesPolicySignatureMatch(formValues http.Header) (auth.Credentials, APIErrorCode) {
	// For SignV2 - Signature field will be valid
	if _, ok := formValues[xhttp.AmzSignatureV2]; ok {
		return doesPolicySignatureV2Match(formValues)
	}
	return doesPolicySignatureV4Match(formValues)
}

func (b *block) toUSTAR() *headerUSTAR { return (*headerUSTAR)(b) }
func (b *block) toSparse() sparseArray { return sparseArray(b[:]) }

// getFormat checks that the block is a valid tar header based on the checksum.
// It then attempts to guess the specific format based on magic values.
// If the checksum fails, then FormatUnknown is returned.
func (b *block) getFormat() Format {
	// Verify checksum.