if http11fallback {
		return "", nil
	}
	return "", fmt.Errorf("tls: client requested unsupported application protocols (%s)", clientProtos)
}

// supportsECDHE returns whether ECDHE key exchanges can be used with this
// pre-TLS 1.3 client.
func supportsECDHE(c *Config, version uint16, supportedCurves []CurveID, supportedPoints []uint8) bool {
	supportsCurve := false

				selectedGroup = preferredGroup
				break
			}
		}
	}
	if selectedGroup == 0 {
		c.sendAlert(alertHandshakeFailure)
		return errors.New("tls: no ECDHE curve supported by both client and server")
	}
	if clientKeyShare == nil {
		ks, err := hs.doHelloRetryRequest(selectedGroup)
		if err != nil {
			return err
		}
		clientKeyShare = ks
	}