+ "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            + "1234567890";
    assertThat(xmlEscaper.escape(s)).isEqualTo(s);

    // Test ASCII control characters.
    for (char ch = 0; ch < 0x20; ch++) {
      if (ch == '\t' || ch == '\n' || ch == '\r') {
        // Only these whitespace chars are permitted in XML,
        if (shouldEscapeWhitespaceChars) {

            + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            + "1234567890";
    assertThat(xmlEscaper.escape(s)).isEqualTo(s);

    // Test ASCII control characters.
    for (char ch = 0; ch < 0x20; ch++) {
      if (ch == '\t' || ch == '\n' || ch == '\r') {
        // Only these whitespace chars are permitted in XML,
        if (shouldEscapeWhitespaceChars) {

            }

            b and 0x40 == 0x40 -> {
              // 01NNNNNN
              val index = readInt(b, PREFIX_6_BITS)
              readLiteralHeaderWithIncrementalIndexingIndexedName(index - 1)
            }

            b and 0x20 == 0x20 -> {
              // 001NNNNN
              maxDynamicTableByteCount = readInt(b, PREFIX_5_BITS)

      }

      // We can't use .clone() because of GWT.
      byte[] newDecodabet = Arrays.copyOf(decodabet, decodabet.length);
      for (int upper = 'A'; upper <= 'Z'; upper++) {
        int lower = upper | 0x20;
        byte decodeUpper = decodabet[upper];
        byte decodeLower = decodabet[lower];
        if (decodeUpper == -1) {
          newDecodabet[upper] = decodeLower;
        } else {
          checkState(

    continuation.left = length
    continuation.padding = padding
    continuation.flags = flags
    continuation.streamId = streamId

    // TODO: Concat multi-value headers with 0x0, except COOKIE, which uses 0x3B, 0x20.
    // http://tools.ietf.org/html/draft-ietf-httpbis-http2-17#section-8.1.2.5
    hpackReader.readHeaders()
    return hpackReader.getAndResetHeaderList()
  }

  @Throws(IOException::class)

   * @return {@code true} if the argument is a 6to4 address
   */
  public static boolean is6to4Address(Inet6Address ip) {
    byte[] bytes = ip.getAddress();
    return (bytes[0] == (byte) 0x20) && (bytes[1] == (byte) 0x02);
  }

  /**
   * Returns the IPv4 address embedded in a 6to4 address.
   *
   * @param ip {@link Inet6Address} to be examined for embedded IPv4 in 6to4 address

      // TODO(cpovirk): Use SourceCodeEscapers if it is added to Guava.
      StringBuilder escapedInput = new StringBuilder();
      for (char c : input.toCharArray()) {
        if (c >= 0x20 && c <= 0x7E) {
          escapedInput.append(c);
        } else {
          escapedInput.append(String.format("\\u%04x", (int) c));
        }
      }

      // TODO(cpovirk): Use SourceCodeEscapers if it is added to Guava.
      StringBuilder escapedInput = new StringBuilder();
      for (char c : input.toCharArray()) {
        if (c >= 0x20 && c <= 0x7E) {
          escapedInput.append(c);
        } else {
          escapedInput.append(String.format("\\u%04x", (int) c));
        }
      }

    assertFailsWith<IllegalArgumentException> {
      Request.Builder().addHeader("a b", "c")
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Unexpected char 0x20 at 1 in header name: a b")
    }
  }

  @Test
  fun requestHeaderNameWithTabForbidden() {
    assertFailsWith<IllegalArgumentException> {
      Request.Builder().addHeader("a\tb", "c")

              new byte[] {(byte) 0xcd, (byte) 0xab, (byte) 0x00, (byte) 0x00},
              0x0000abcd,
              null,
              "cdab0000"),
          new ExpectedHashCode(
              new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x00,
                (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00
              },
              0x00abcdef,
              0x0000000000abcdefL,