code: func (wfe *WebFrontEndImpl) validSelfAuthenticatedPOST(
  	request *http.Request,
  	logEvent *web.RequestEvent) ([]byte, *jose.JSONWebKey, *probs.ProblemDetails) {
  	// Parse the JWS from the POST request
  	jws, prob := wfe.parseJWSRequest(request)
  	if prob != nil {
  		return nil, nil, prob
  	}
  	// Extract and validate the embedded JWK from the parsed JWS
  	return wfe.validSelfAuthenticatedJWS(jws, request, logEvent)
  }
docs: // validSelfAuthenticatedPOST checks that a given POST request has a valid JWS
  // using `validSelfAuthenticatedJWS`.