cc := e.clientConfig
	if cc == nil {
		return nil, nil
	}
	var address string
	if cc.URL != nil {
		address = *cc.URL
	}
	var certPool *x509.CertPool
	if len(cc.CABundle) > 0 {
		certPool = x509.NewCertPool()
		certPool.AppendCertsFromPEM(cc.CABundle)
	} else {
		var err error
		certPool, err = x509.SystemCertPool()
		if err != nil {
			return nil, err
		}
	}

pkg crypto/x509, func MarshalPKCS1PrivateKey(*rsa.PrivateKey) []uint8
pkg crypto/x509, func MarshalPKIXPublicKey(interface{}) ([]uint8, error)
pkg crypto/x509, func NewCertPool() *CertPool
pkg crypto/x509, func ParseCRL([]uint8) (*pkix.CertificateList, error)
pkg crypto/x509, func ParseCertificate([]uint8) (*Certificate, error)
pkg crypto/x509, func ParseCertificates([]uint8) ([]*Certificate, error)