val cipherSuite =
        when (val cipherSuiteString = checkNotNull(cipherSuite) { "cipherSuite == null" }) {
          "TLS_NULL_WITH_NULL_NULL", "SSL_NULL_WITH_NULL_NULL" -> {
            throw IOException("cipherSuite == $cipherSuiteString")
          }
          else -> CipherSuite.forJavaName(cipherSuiteString)
        }

      val tlsVersionString = checkNotNull(protocol) { "tlsVersion == null" }