@Override
    protected Event doExecuteInternal(final RequestContext requestContext) {
        val authentication = WebUtils.getAuthentication(requestContext);
        val uid = resolvePrincipal(authentication.getPrincipal(), requestContext).getId();
        if (registry.isYubiKeyRegisteredFor(uid)) {
            return success();
        }
        return eventFactory.event(this, CasWebflowConstants.TRANSITION_ID_REGISTER);
    }
This is {@link YubiKeyAccountCheckRegistrationAction}.

@author Misagh Moayyed
@since 5.2.0
support/cas-server-support-yubikey-core/src/main/java/org/apereo/cas/adaptors/yubikey/web/flow/YubiKeyAccountCheckRegistrationAction.java