public static void putMultifactorAuthenticationProvider(final RequestContext context, final MultifactorAuthenticationProvider provider) {
        context.getFlowScope().put(CasWebflowConstants.VAR_ID_MFA_PROVIDER_ID, provider.getId());
    }
Add the mfa provider id into flow scope.

@param context  request context
@param provider the mfa provider
core/cas-server-core-webflow-mfa-api/src/main/java/org/apereo/cas/web/flow/util/MultifactorAuthenticationWebflowUtils.java