code: public String getProxyTicketFor(final String service) {
          if (this.attributePrincipal != null) {
              logger.debug("Requesting PT from principal: {} and for service: {}", attributePrincipal, service);
              final String pt = this.attributePrincipal.getProxyTicketFor(service);
              logger.debug("Get PT: {}", pt);
              return pt;
          }
          return null;
      }
docs: Get a proxy ticket for a given service.
  
  @param service the CAS service
  @return the proxy ticket for the given service