*       Stream.map}).
 *   <li><b>Do not</b> call {@link #doForward} or {@link #doBackward} directly; these exist only to
 *       be overridden.
 * </ul>
 *
 * <h3>Example</h3>
 *
 * <pre>
 *   return new Converter&lt;Integer, String&gt;() {
 *     protected String doForward(Integer i) {
 *       return Integer.toHexString(i);
 *     }
 *

 *       Stream.map}).
 *   <li><b>Do not</b> call {@link #doForward} or {@link #doBackward} directly; these exist only to
 *       be overridden.
 * </ul>
 *
 * <h3>Example</h3>
 *
 * <pre>
 *   return new Converter&lt;Integer, String&gt;() {
 *     protected String doForward(Integer i) {
 *       return Integer.toHexString(i);
 *     }
 *

			if nt == "" {
				nt = network
			}
			addr := dnsServer
			if addr == "" {
				addr = address
			}
			return d.DialContext(ctx, nt, addr)
		},
	}
}

// doForward sends the requests and collect the responses.
func doForward(ctx context.Context, cfg *Config, e *executor, doReq func(context.Context, *Config, int) (string, error)) (*proto.ForwardEchoResponse, error) {
	// make the timeout apply to the entire set of requests

		defer func() { _ = conn.Close() }()
		getConn = func() (*grpc.ClientConn, func(), error) {
			return conn, func() {}, nil
		}
	}

	call := grpcCall{
		e:       c.e,
		getConn: getConn,
	}
	return doForward(ctx, cfg, c.e, call.makeRequest)
}

func (c *xdsProtocol) Close() error {
	return nil
}

func newXDSConnection(cfg *Config) (*grpc.ClientConn, error) {
	var opts []grpc.DialOption

	// transport security

      implements Serializable {

    private final Class<T> enumClass;

    StringConverter(Class<T> enumClass) {
      this.enumClass = checkNotNull(enumClass);
    }

    @Override
    protected T doForward(String value) {
      return Enum.valueOf(enumClass, value);
    }

    @Override
    protected String doBackward(T enumValue) {
      return enumValue.name();
    }

    @Override

	e *executor
}

func newUDPProtocol(e *executor) protocol {
	return &udpProtocol{e: e}
}

func (c *udpProtocol) ForwardEcho(ctx context.Context, cfg *Config) (*proto.ForwardEchoResponse, error) {
	return doForward(ctx, cfg, c.e, c.makeRequest)
}

func (c *udpProtocol) makeRequest(ctx context.Context, cfg *Config, requestID int) (string, error) {
	conn, err := newUDPConnection(cfg)
	if err != nil {
		return "", err
	}

}

func newWebsocketProtocol(e *executor) protocol {
	return &websocketProtocol{e: e}
}

func (c *websocketProtocol) ForwardEcho(ctx context.Context, cfg *Config) (*proto.ForwardEchoResponse, error) {
	return doForward(ctx, cfg, c.e, c.makeRequest)
}

func (c *websocketProtocol) Close() error {
	return nil
}

func (c *websocketProtocol) makeRequest(ctx context.Context, cfg *Config, requestID int) (string, error) {

	e *executor
}

func newTLSProtocol(e *executor) protocol {
	return &tlsProtocol{e: e}
}

func (c *tlsProtocol) ForwardEcho(ctx context.Context, cfg *Config) (*proto.ForwardEchoResponse, error) {
	return doForward(ctx, cfg, c.e, c.makeRequest)
}

func (c *tlsProtocol) makeRequest(ctx context.Context, cfg *Config, requestID int) (string, error) {
	conn, err := newTLSConnection(cfg)
	if err != nil {
		return "", err
	}

	e *executor
}

func newDNSProtocol(e *executor) protocol {
	return &dnsProtocol{e: e}
}

func (c *dnsProtocol) ForwardEcho(ctx context.Context, cfg *Config) (*proto.ForwardEchoResponse, error) {
	return doForward(ctx, cfg, c.e, c.makeRequest)
}

type dnsRequest struct {
	hostname  string
	dnsServer string
	query     string
	protocol  string
}

func checkIn(got string, want ...string) error {

      implements Serializable {

    private final Class<T> enumClass;

    StringConverter(Class<T> enumClass) {
      this.enumClass = checkNotNull(enumClass);
    }

    @Override
    protected T doForward(String value) {
      return Enum.valueOf(enumClass, value);
    }

    @Override
    protected String doBackward(T enumValue) {
      return enumValue.name();
    }

    @Override