@Override
    protected Event doExecuteInternal(final RequestContext requestContext) {
        WebUtils.putGraphicalUserAuthenticationEnabled(requestContext, Boolean.TRUE);
        if (!WebUtils.containsGraphicalUserAuthenticationUsername(requestContext)) {
            return eventFactory.event(this, CasWebflowConstants.TRANSITION_ID_GUA_GET_USERID);
        }
        return null;
    }
This is {@link PrepareForGraphicalAuthenticationAction}.

@author Misagh Moayyed
@since 5.1.0
support/cas-server-support-gua/src/main/java/org/apereo/cas/web/flow/PrepareForGraphicalAuthenticationAction.java