response.isChunked -> -1L
      else -> response.headersContentLength()
    }
  }

  override fun openResponseBodySource(response: Response): Source {
    return when {
      !response.promisesBody() -> newFixedLengthSource(0)
      response.isChunked -> newChunkedSource(response.request.url)
      else -> {
        val contentLength = response.headersContentLength()
        if (contentLength != -1L) {

  currentThread.name = name
  try {
    block()
  } finally {
    currentThread.name = oldName
  }
}

/** Returns the Content-Length as reported by the response headers. */
internal fun Response.headersContentLength(): Long {
  return headers["Content-Length"]?.toLongOrDefault(-1L) ?: -1L
}

/** Returns an immutable copy of this. */
internal fun <T> List<T>.toImmutableList(): List<T> {