* The pool will routinely try to pre-emptively open connections to satisfy this minimum.
     * Connections will still be closed if they idle beyond the keep-alive but will be replaced.
     */
    @JvmField val minimumConcurrentCalls: Int = 0,
    /** How long to wait to retry pre-emptive connection attempts that fail. */
    @JvmField val backoffDelayMillis: Long = 60 * 1000,

    // Connections are created as soon as a policy is set
    setPolicy(pool, address, ConnectionPool.AddressPolicy(2))
    assertThat(pool.connectionCount()).isEqualTo(2)

    // Connections are replaced if they idle out or are evicted from the pool
    evictAllConnections(pool)
    assertThat(pool.connectionCount()).isEqualTo(2)
    forceConnectionsToExpire(pool, expireTime)

     */
    open fun url(url: URL) = url(url.toString().toHttpUrl())

    /**
     * Sets the header named [name] to [value]. If this request already has any headers
     * with that name, they are all replaced.
     */
    open fun header(
      name: String,
      value: String,
    ) = commonHeader(name, value)

    /**
     * Adds a header with [name] and [value]. Prefer this method for multiply-valued

        connectionUser = connectionUser,
        routes = routes,
        requireMultiplexed = planToReplace != null && planToReplace.isReady,
      ) ?: return null

    // If we coalesced our connection, remember the replaced connection's route. That way if the
    // coalesced connection later fails we don't waste a valid route.
    if (planToReplace != null) {
      nextRouteToTry = planToReplace.route
      planToReplace.closeQuietly()

   * served by the first enqueued response; the second request by the second enqueued response; and
   * so on.
   *
   * @throws ClassCastException if the default dispatcher has been
   * replaced with [setDispatcher][dispatcher].
   */
  fun enqueue(response: MockResponse) = (dispatcher as QueueDispatcher).enqueueResponse(response)

  /**
   * Starts the server on the loopback interface for the given port.

        "A", "a1", "B", "b2", "B", "b3", "Content-Length", "4",
      ),
    )

    // The original 'A' header is retained because the network response doesn't have one.
    // The original 'B' headers are replaced by the network response.
    // The network's 'C' header is added.
    val response2 = get(server.url("/"))
    assertThat(response2.body.string()).isEqualTo("abcd")
    assertThat(response2.headers).isEqualTo(