responseDequeuedLatches[responseIndex].countDown()
      requestCanceledLatches[responseIndex].await()
      responseIndex++
      return response
    }
  }

  /** Make a call and canceling it as soon as it's accepted by the server.  */
  private fun callAndCancel(
    expectedSequenceNumber: Int,
    responseDequeuedLatch: CountDownLatch?,
    requestCanceledLatch: CountDownLatch?,
  ) {

 *
 * Note that an allocation may be released before its stream is completed. This is intended to make
 * bookkeeping easier for the caller: releasing the allocation as soon as the terminal stream has
 * been found. But only complete the stream once its data stream has been exhausted.
 */
interface Connection {
  /** Returns the route used by this connection. */
  fun route(): Route

  /**