@Override
    protected Event doExecuteInternal(final RequestContext requestContext) {
        val tgtId = WebUtils.getTicketGrantingTicketId(requestContext);
        if (StringUtils.isBlank(tgtId)) {
            return new Event(this, CasWebflowConstants.TRANSITION_ID_TICKET_GRANTING_TICKET_NOT_EXISTS);
        }
        try {
            val ticket = ticketRegistry.getTicket(tgtId, Ticket.class);
            LOGGER.trace("Located ticket with id [{}]", ticket.getId());
            return new Event(this, CasWebflowConstants.TRANSITION_ID_TICKET_GRANTING_TICKET_VALID);
        } catch (final Exception e) {
            LOGGER.trace("Could not retrieve ticket id [{}] from registry.", e.getMessage());
        }
        return new Event(this, CasWebflowConstants.TRANSITION_ID_TICKET_GRANTING_TICKET_INVALID);
    }
Webflow action that checks whether the TGT in the request context is valid.

@author Marvin S. Addison
@since 4.0.0
support/cas-server-support-actions-core/src/main/java/org/apereo/cas/web/flow/login/TicketGrantingTicketCheckAction.java