return buildString {
        val buffer = Buffer().writeUtf8(s)
        while (!buffer.exhausted()) {
          val c = buffer.readUtf8CodePoint()
          if (c != '\\'.code) {
            append(c.toChar())
            continue
          }
          when (buffer.readUtf8CodePoint()) {
            '\\'.code -> append('\\')
            '#'.code -> append('#')
            'n'.code -> append('\n')

      writeUtf8(if (alreadyEncoded) "+" else "%2B")
    } else if (codePoint < 0x20 ||
      codePoint == 0x7f ||
      codePoint >= 0x80 && !unicodeAllowed ||
      codePoint.toChar() in encodeSet ||
      codePoint == '%'.code &&
      (!alreadyEncoded || strict && !input.isPercentEncoded(i, limit))
    ) {
      // Percent encode this character.
      if (encodedCharBuffer == null) {

        .body("ABCD")
        .build(),
    )
    val call = client.newCall(newRequest("/"))
    val response = call.execute()
    val inputStream = response.body.byteStream()
    assertThat(inputStream.read().toChar()).isEqualTo('A')
    call.cancel()
    assertFailsWith<IOException> {
      // Reading 'B' may succeed if it's buffered.
      inputStream.read()

  private fun largeHeaders(): List<Header> {
    val nameValues = arrayOfNulls<String>(32)
    val chars = CharArray(512)
    var i = 0
    while (i < nameValues.size) {
      Arrays.fill(chars, i.toChar())
      val string = String(chars)
      nameValues[i++] = string
      nameValues[i++] = string
    }
    return headerEntries(*nameValues)
  }

  private fun writeMedium(
    sink: BufferedSink,

0181          ; mapped                 ; 0253          # 1.1  LATIN CAPITAL LETTER B WITH HOOK
0182          ; mapped                 ; 0183          # 1.1  LATIN CAPITAL LETTER B WITH TOPBAR
0183          ; valid                                  # 1.1  LATIN SMALL LETTER B WITH TOPBAR
0184          ; mapped                 ; 0185          # 1.1  LATIN CAPITAL LETTER TONE SIX
0185          ; valid                                  # 1.1  LATIN SMALL LETTER TONE SIX