// Treating this use case as user error
      server.protocols = listOf(Protocol.H2_PRIOR_KNOWLEDGE, Protocol.H2_PRIOR_KNOWLEDGE)
      fail<Any>()
    } catch (expected: IllegalArgumentException) {
      assertThat(expected.message).isEqualTo(
        "protocols containing h2_prior_knowledge cannot use other protocols: " +
          "[h2_prior_knowledge, h2_prior_knowledge]",
      )
    }
  }

  @Test

    this.withLock {
      successCount++
    }
  }

  @Throws(IOException::class)
  fun start() {
    idleAtNs = System.nanoTime()
    if (protocol == Protocol.HTTP_2 || protocol == Protocol.H2_PRIOR_KNOWLEDGE) {
      startHttp2()
    }
  }

  @Throws(IOException::class)
  private fun startHttp2() {
    val socket = this.socket!!
    val source = this.source!!
    val sink = this.sink!!

    assertThat(get("http/1.1")).isEqualTo(Protocol.HTTP_1_1)
    assertThat(get("spdy/3.1")).isEqualTo(Protocol.SPDY_3)
    assertThat(get("h2")).isEqualTo(Protocol.HTTP_2)
    assertThat(get("h2_prior_knowledge")).isEqualTo(Protocol.H2_PRIOR_KNOWLEDGE)
    assertThat(get("quic")).isEqualTo(Protocol.QUIC)
    assertThat(get("h3")).isEqualTo(Protocol.HTTP_3)
    assertThat(get("h3-29")).isEqualTo(Protocol.HTTP_3)
  }

/**
 * Used when we were unsuccessful in the planning phase of a connection:
 *
 *  * A DNS lookup failed
 *  * The configuration is incapable of carrying the request, such as when the client is configured
 *    to use `H2_PRIOR_KNOWLEDGE` but the URL's scheme is `https:`.
 *  * Preemptive proxy authentication failed.
 *
 * Planning failures are not necessarily fatal. For example, even if we can't DNS lookup the first

    dnsResults =
      listOf(
        localhostIpv4,
        localhostIpv6,
        TestUtil.UNREACHABLE_ADDRESS_IPV4.address,
      )
    serverIpv4.protocols = listOf(Protocol.H2_PRIOR_KNOWLEDGE)
    serverIpv6.protocols = listOf(Protocol.H2_PRIOR_KNOWLEDGE)

    // Yield the first IP address so the second IP address completes first.
    val firstConnectLatch = CountDownLatch(1)
    val socketFactory =

    assertFailsWith<IllegalArgumentException> {
      OkHttpClient.Builder()
        .protocols(listOf(Protocol.H2_PRIOR_KNOWLEDGE, Protocol.H2_PRIOR_KNOWLEDGE))
    }.also { expected ->
      assertThat(expected.message).isEqualTo(
        "protocols containing h2_prior_knowledge cannot use other protocols: " +
          "[h2_prior_knowledge, h2_prior_knowledge]",
      )
    }
  }

    logRecorder
      .assertLogMatch(Regex("""cacheConditionalHit: Response\{protocol=h2, code=200, message=, url=$url\}"""))
      .assertLogMatch(Regex("""cacheHit: Response\{protocol=h2, code=200, message=, url=$url\}"""))
      .assertLogMatch(Regex("""cacheMiss"""))
      .assertLogMatch(Regex("""satisfactionFailure: Response\{protocol=h2, code=200, message=, url=$url\}"""))
      .assertNoMoreLogs()
  }

        connectTls(sslSocket, connectionSpec)
        user.secureConnectEnd(handshake)
      } else {
        socket = rawSocket
        protocol =
          when {
            Protocol.H2_PRIOR_KNOWLEDGE in route.address.protocols -> Protocol.H2_PRIOR_KNOWLEDGE
            else -> Protocol.HTTP_1_1
          }
      }

      val connection =
        RealConnection(
          taskRunner = taskRunner,

    set(value) {
      val protocolList = value.toImmutableList()
      require(Protocol.H2_PRIOR_KNOWLEDGE !in protocolList || protocolList.size == 1) {
        "protocols containing h2_prior_knowledge cannot use other protocols: $protocolList"
      }
      require(Protocol.HTTP_1_1 in protocolList || Protocol.H2_PRIOR_KNOWLEDGE in protocolList) {
        "protocols doesn't contain http/1.1: $protocolList"
      }

        throw UnknownServiceException(
          "CLEARTEXT communication to $host not permitted by network security policy",
        )
      }
    } else {
      if (Protocol.H2_PRIOR_KNOWLEDGE in route.address.protocols) {
        throw UnknownServiceException("H2_PRIOR_KNOWLEDGE cannot be used with HTTPS")
      }
    }

    val tunnelRequest =
      when {
        route.requiresTunnel() -> createTunnelRequest(route)