code: private boolean validateAssertion(final HttpServletRequest request, final String serviceTicketId, final Assertion assertion, final Service service) {
          for (val spec : serviceValidateConfigurationContext.getValidationSpecifications()) {
              spec.reset();
              val binder = new ServletRequestDataBinder(spec, "validationSpecification");
              initBinder(request, binder);
              binder.bind(request);
              if (!spec.isSatisfiedBy(assertion, request)) {
                  LOGGER.warn("Service ticket [{}] does not satisfy validation specification.", serviceTicketId);
                  return false;
              }
          }
          enforceTicketValidationAuthorizationFor(request, service, assertion);
          return true;
      }
docs: Validate assertion.
  
  @param request         the request
  @param serviceTicketId the service ticket id
  @param assertion       the assertion
  @param service         the service
  @return true/false