try {
      // SSLSocket.getApplicationProtocol returns "" if application protocols values will not
      // be used. Observed if you didn't specify SSLParameters.setApplicationProtocols
      when (val protocol = sslSocket.applicationProtocol) {
        null, "" -> null
        else -> protocol
      }
    } catch (e: UnsupportedOperationException) {

      // Enable session tickets.
      Conscrypt.setUseSessionTickets(sslSocket, true)

      // Enable ALPN.
      val names = Platform.alpnProtocolNames(protocols)
      Conscrypt.setApplicationProtocols(sslSocket, names.toTypedArray())
    }
  }

  companion object {
    val factory =
      object : DeferredSocketAdapter.Factory {

      // Enable session tickets.
      Conscrypt.setUseSessionTickets(sslSocket, true)

      // Enable ALPN.
      val names = alpnProtocolNames(protocols)
      Conscrypt.setApplicationProtocols(sslSocket, names.toTypedArray())
    } else {
      super.configureTlsExtensions(sslSocket, hostname, protocols)
    }
  }

  override fun getSelectedProtocol(sslSocket: SSLSocket): String? =

    try {
      // SSLSocket.getApplicationProtocol returns "" if application protocols values will not
      // be used. Observed if you didn't specify SSLParameters.setApplicationProtocols
      when (val protocol = sslSocket.applicationProtocol) {
        null, "" -> null
        else -> protocol
      }
    } catch (e: UnsupportedOperationException) {