public String getZoneId() {
        return StringUtils.isBlank(zoneId)
            ? ZoneOffset.UTC.getId()
            : SpringExpressionLanguageValueResolver.getInstance().resolve(zoneId);
    }
The {@link TimeBasedRegisteredServiceAccessStrategy} is responsible for
enforcing CAS authorization strategy based on a configured start/end time.

@author Misagh Moayyed
@since 4.2
core/cas-server-core-services-api/src/main/java/org/apereo/cas/services/TimeBasedRegisteredServiceAccessStrategy.java