val s = sslSocket as BCSSLSocket

    return when (val protocol = s.applicationProtocol) {
      null, "" -> null
      else -> protocol
    }
  }

  override fun configureTlsExtensions(
    sslSocket: SSLSocket,
    hostname: String?,
    protocols: List<Protocol>,
  ) {
    // No TLS extensions if the socket class is custom.
    if (matchesSocket(sslSocket)) {