namePrefix, hdr.Name = prefix, suffix
	}

	// Pack the main header.
	var f formatter
	blk := tw.templateV7Plus(hdr, f.formatString, f.formatOctal)
	f.formatString(blk.toUSTAR().prefix(), namePrefix)
	blk.setFormat(FormatUSTAR)
	if f.err != nil {
		return f.err // Should never happen since header is validated
	}
	return tw.writeRawHeader(blk, hdr.Size, hdr.Typeflag)
}

		// Write the initial GNU header.
		var blk block
		gnu := blk.toGNU()
		sparse := gnu.sparse()
		copy(gnu.realSize(), size)
		sps = populateSparseMap(sparse, sps)
		if format != FormatUnknown {
			blk.setFormat(format)
		}
		out = append(out, blk[:]...)

		// Write extended sparse blocks.
		for len(sps) > 0 {
			var blk block
			sps = populateSparseMap(blk.toSparse(), sps)
			out = append(out, blk[:]...)

            return "HmacMD5";
          }

          @Override
          public byte[] getEncoded() {
            return new byte[8];
          }

          @Override
          public String getFormat() {
            return "RAW";
          }
        };
    assertEquals(
        "ad262969c53bc16032f160081c4a07a0",
        Hashing.hmacMd5(customKey)

  private static String hmacToString(String methodName, Key key) {
    return "Hashing."
        + methodName
        + "(Key[algorithm="
        + key.getAlgorithm()
        + ", format="
        + key.getFormat()
        + "])";
  }

  /**
   * Returns a hash function implementing the CRC32C checksum algorithm (32 hash bits) as described
   * by RFC 3720, Section 12.1.
   *

		var blk block
		copy(blk[:], b.Bytes())
		prefix := string(blk.toUSTAR().prefix())
		prefix, _, _ = strings.Cut(prefix, "\x00") // Truncate at the NUL terminator
		if blk.getFormat() == FormatGNU && len(prefix) > 0 && strings.HasPrefix(name, prefix) {
			t.Errorf("test %d, found prefix in GNU format: %s", i, prefix)
		}

		tr := NewReader(&b)
		hdr, err := tr.Next()