certificatePinner.check(address.url.host) {
        handshake.peerCertificates.map { it as X509Certificate }
      }

      // Success! Save the handshake and the ALPN protocol.
      val maybeProtocol =
        if (connectionSpec.supportsTlsExtensions) {
          Platform.get().getSelectedProtocol(sslSocket)
        } else {
          null
        }

problems. If your service has multiple IP addresses, OkHttp will attempt alternate addresses if the
first connect fails. This is necessary for IPv4+IPv6 and services hosted in redundant data
centers. OkHttp supports modern TLS features (TLS 1.3, ALPN, certificate pinning). It can be
configured to fall back for broad connectivity.

Using OkHttp is easy. Its request/response API is designed with fluent builders and immutability. It

import org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement

/**
 * Access to platform-specific features.
 *
 * ### Session Tickets
 *
 * Supported on Android 2.3+.
 * Supported on JDK 8+ via Conscrypt.
 *
 * ### ALPN (Application Layer Protocol Negotiation)
 *
 * Supported on Android 5.0+.
 *
 * Supported on OpenJDK 8 via the JettyALPN-boot library or Conscrypt.
 *
 * Supported on OpenJDK 9+ via SSLParameters and SSLSocket features.

        implementation(libs.junit.vintage.engine)

        implementation(libs.robolectric)
      }
    }
  }
}

if (platform == "jdk8alpn") {
  // Add alpn-boot on Java 8 so we can use HTTP/2 without a stable API.
  val alpnBootVersion = alpnBootVersion()
  if (alpnBootVersion != null) {
    val alpnBootJar = configurations.detachedConfiguration(

  /**
   * True if ALPN is used on incoming HTTPS connections to negotiate a protocol like HTTP/1.1 or
   * HTTP/2. This is true by default; set to false to disable negotiation and restrict connections
   * to HTTP/1.1.
   */
  public var protocolNegotiationEnabled: Boolean = true

  /**
   * The protocols supported by ALPN on incoming HTTPS connections in order of preference. The list

    5.x upgrade as an opportunity to remove very obsolete APIs.
 *  Fix: Recover gracefully when Android's `NativeCrypto` crashes with `"ssl == null"`. This occurs
    when OkHttp retrieves ALPN state on a closed connection.
 *  Upgrade: [Kotlin 1.6.21][kotlin_1_6_21].
 *  Upgrade: [Okio 3.1.0][okio_3_1_0].


## Version 5.0.0-alpha.6

_2022-03-14_

    } catch (e: IOException) {
      RecordedResponse(request, null, null, null, e)
    }
  }

  /**
   * Tests that use this will fail unless boot classpath is set. Ex. `-Xbootclasspath/p:/tmp/alpn-boot-8.0.0.v20140317`
   */
  private fun enableProtocol(protocol: Protocol) {
    enableTls()
    client =
      client
        .newBuilder()
        .protocols(listOf(protocol, Protocol.HTTP_1_1))