var proxySelector: ProxySelector = RecordingProxySelector()
  var proxyAuthenticator: Authenticator = RecordingOkAuthenticator("password", null)
  var connectionSpecs: List<ConnectionSpec> =
    listOf(
      ConnectionSpec.MODERN_TLS,
      ConnectionSpec.COMPATIBLE_TLS,
      ConnectionSpec.CLEARTEXT,
    )
  var protocols: List<Protocol> =
    listOf(
      Protocol.HTTP_1_1,
    )

        val tlsEquipPlan = planWithCurrentOrInitialConnectionSpec(connectionSpecs, sslSocket)
        val connectionSpec = connectionSpecs[tlsEquipPlan.connectionSpecIndex]

        // Figure out the next connection spec in case we need a retry.
        retryTlsConnection = tlsEquipPlan.nextConnectionSpec(connectionSpecs, sslSocket)

        connectionSpec.apply(sslSocket, isFallback = tlsEquipPlan.isTlsFallback)

By default, OkHttp will attempt a `MODERN_TLS` connection.  However by configuring the client connectionSpecs you can allow a fall back to `COMPATIBLE_TLS` connection if the modern configuration fails.

```java
OkHttpClient client = new OkHttpClient.Builder()
    .connectionSpecs(Arrays.asList(ConnectionSpec.MODERN_TLS, ConnectionSpec.COMPATIBLE_TLS))
    .build();
```

      this.x509TrustManagerOrNull = trustManager
    }

    fun connectionSpecs(connectionSpecs: List<ConnectionSpec>) =
      apply {
        if (connectionSpecs != this.connectionSpecs) {
          this.routeDatabase = null
        }

        this.connectionSpecs = connectionSpecs.toImmutableList()
      }

    /**

    }

    val sessionIds = mutableListOf<String>()

    enableTls()

    val tlsVersion = TlsVersion.forJavaName(tlsVersion)
    val spec =
      ConnectionSpec
        .Builder(ConnectionSpec.MODERN_TLS)
        .tlsVersions(tlsVersion)
        .build()

    var reuseSession = false

    val sslContext = handshakeCertificates.sslContext()

      builder.socketFactory(SSLSocketFactory.getDefault())
    }
  }

  @Test fun noSslSocketFactoryConfigured() {
    val client =
      OkHttpClient
        .Builder()
        .connectionSpecs(listOf(ConnectionSpec.CLEARTEXT))
        .build()
    assertFailsWith<IllegalStateException> {
      client.sslSocketFactory
    }
  }

  @Test fun nullHostileProtocolList() {
    val nullHostileProtocols =

    client =
      client
        .newBuilder()
        .sslSocketFactory(CustomSSLSocketFactory(client.sslSocketFactory), client.x509TrustManager!!)
        .connectionSpecs(
          listOf(
            ConnectionSpec
              .Builder(ConnectionSpec.MODERN_TLS)
              .supportsTlsExtensions(false)
              .build(),
          ),
        ).eventListener(
          object : EventListener() {

import org.robolectric.RobolectricTestRunner
import org.robolectric.shadows.ShadowLog

@RunWith(RobolectricTestRunner::class)
class AndroidLoggingTest {
  val clientBuilder =
    OkHttpClient.Builder().connectionSpecs(listOf(ConnectionSpec.CLEARTEXT)).dns {
      throw UnknownHostException("shortcircuit")
    }

  val request = Request("http://google.com/robots.txt".toHttpUrl())

  @Test
  fun testHttpLoggingInterceptor() {

 * available in JDK11 or Conscrypt.
 */
private val TLS_13 =
  ConnectionSpec
    .Builder(true)
    .cipherSuites(*TLS13_CIPHER_SUITES.toTypedArray())
    .tlsVersions(TlsVersion.TLS_1_3)
    .build()

private val TLS_12 =
  ConnectionSpec
    .Builder(ConnectionSpec.RESTRICTED_TLS)
    .tlsVersions(TlsVersion.TLS_1_2)
    .build()

private fun testClient(

      certificatePinner = useCertificatePinner,
      proxyAuthenticator = proxyAuthenticator,
      proxy = proxy,
      protocols = call.client.protocols,
      connectionSpecs = call.client.connectionSpecs,
      proxySelector = proxySelector,
    )
  }