How to use

forwardToErrorPage

method

in

org.keycloak.adapters.saml.tomcat.SamlAuthenticatorValve

@Override
protected boolean forwardToErrorPageInternal(Request request, HttpServletResponse response, Object loginConfig) throws IOException {
  if (loginConfig == null) return false;
  LoginConfig config = (LoginConfig)loginConfig;
  if (config.getErrorPage() == null) return false;
  forwardToErrorPage(request, (Response)response, config);
  return true;
}