code: public SslProtocol sslProtocol() {
      String protocol = reader.getString(SSL_PROTOCOL, DEFAULT_SSL_PROTOCOL).replace(".", "_");
      try {
        return SslProtocol.valueOf(protocol);
      } catch (IllegalArgumentException e) {
        throw new ConfigurationException("unknown SSL protocol: " + protocol, e);
      }
    }
docs: The SSL Protocol.