protected void addErrorMessageToContext(final Exception exception, final RequestContext requestContext) {
        val messageCode = MessageBundleProperties.DEFAULT_BUNDLE_PREFIX_AUTHN_FAILURE + CasWebflowExceptionCatalog.UNKNOWN;
        WebUtils.addErrorMessageToContext(requestContext, messageCode);
    }
This is {@link GenericCasWebflowExceptionHandler}.

@author Misagh Moayyed
@since 6.1.0
core/cas-server-core-webflow-api/src/main/java/org/apereo/cas/web/flow/authentication/GenericCasWebflowExceptionHandler.java