code: func (p *passTLSClientCert) modifyRequestHeaders(logger logrus.FieldLogger, r *http.Request) {
  	if p.pem {
  		if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 {
  			r.Header.Set(xForwardedTLSClientCert, getXForwardedTLSClientCert(logger, r.TLS.PeerCertificates))
  		} else {
  			logger.Warn("Try to extract certificate on a request without TLS")
  		}
  	}
  
  	if p.info != nil {
  		if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 {
  			headerContent := p.getXForwardedTLSClientCertInfo(r.TLS.PeerCertificates)
  			r.Header.Set(xForwardedTLSClientCertInfo, url.QueryEscape(headerContent))
  		} else {
  			logger.Warn("Try to extract certificate on a request without TLS")
  		}
  	}
  }
docs: // modifyRequestHeaders set the wanted headers with the certificates information.