@Override
    protected Event doExecuteInternal(final RequestContext context) {
        try {
            val request = WebUtils.getHttpServletRequestFromExternalWebflowContext(context);
            val wa = request.getParameter(WA);
            if (StringUtils.isNotBlank(wa) && wa.equalsIgnoreCase(WSIGNIN)) {
                wsFederationResponseValidator.validateWsFederationAuthenticationRequest(context);
                return super.doExecuteInternal(context);
            }
            return wsFederationRequestBuilder.buildAuthenticationRequestEvent(context);
        } catch (final Throwable ex) {
            LoggingUtils.error(LOGGER, ex);
            throw UnauthorizedServiceException.wrap(ex);
        }
    }
This class represents an action in the webflow to retrieve WsFederation information on the callback url which is
the webflow url (/login).

@author John Gasper
@since 4.2.0
support/cas-server-support-wsfederation-webflow/src/main/java/org/apereo/cas/web/flow/WsFederationAction.java