Thread thread;
    TransportException te;

    protected HashMap response_map = new HashMap( 4 );

    protected abstract void makeKey( Request request ) throws IOException;
    protected abstract Request peekKey() throws IOException;
    protected abstract void doSend( Request request ) throws IOException;
    protected abstract void doRecv( Response response ) throws IOException;
    protected abstract void doSkip() throws IOException;

): String? = headers[name] ?: defaultValue

@Throws(IOException::class)
fun Response.commonPeekBody(byteCount: Long): ResponseBody {
  val peeked = body.source().peek()
  val buffer = Buffer()
  peeked.request(byteCount)
  buffer.write(peeked, minOf(byteCount, peeked.buffer.size))
  return buffer.asResponseBody(body.contentType(), buffer.size)
}

fun Response.commonNewBuilder(): Response.Builder = Response.Builder(this)

    while (true) {
      if (peek == null) {
        peek = readToken()
        if (skipCommasAndWhitespace()) break // We peeked a scheme name followed by ','.
        eqCount = skipAll('='.code.toByte())
      }
      if (eqCount == 0) break // We peeked a scheme name.
      if (eqCount > 1) return // Unexpected '=' characters.
      if (skipCommasAndWhitespace()) return // Unexpected ','.

  /**
   * Returns a value from this adapter.
   *
   * This must always return a value, though it doesn't necessarily need to consume data from
   * [reader]. For example, if the reader's peeked tag isn't readable by this adapter, it may return
   * a default value.
   *
   * If this does read a value, it starts with the tag and length, and reads an entire value,
   * including any potential composed values.
   *