code: func skipAuthenticationHeader(request *http.Request, body []byte) bool {
  	stringBody := string(body)
  
  	return strings.Contains(request.URL.String(), "/oauth/token") &&
  		request.Method == http.MethodPost &&
  		(strings.Contains(stringBody, "grant_type=refresh_token") ||
  			strings.Contains(stringBody, "grant_type=password") ||
  			strings.Contains(stringBody, "grant_type=client_credentials"))
  }
docs: // The authentication header is not added to token refresh requests or login
  // requests.