}

  @Throws(IOException::class)
  fun readResponseHeaders(expectContinue: Boolean): Response.Builder? {
    try {
      val result = codec.readResponseHeaders(expectContinue)
      result?.initExchange(this)
      return result
    } catch (e: IOException) {
      call.eventListener.responseFailed(call, e)
      trackFailure(e)
      throw e
    }
  }

          else -> SequentialExchangeFinder(routePlanner)
        }
    }
  }

  /** Finds a new or pooled connection to carry a forthcoming request and response. */
  internal fun initExchange(chain: RealInterceptorChain): Exchange {
    withLock {
      check(expectMoreExchanges) { "released" }
      check(!responseBodyOpen && !requestBodyOpen && !socketSourceOpen && !socketSinkOpen)
    }