private static void verifyAccessControlFilterPresent(Context context, Http http) {
        FilterChains filterChains = http.getFilterChains();
        Chain<Filter> chain = filterChains.allChains().getComponent(AccessControl.ACCESS_CONTROL_CHAIN_ID);
        if (chain.getInnerComponents().isEmpty()) {
            // No access control filter configured - it's up to a config model plugin to provide an implementation of an access control filter.
            context.illegal("The 'access-control' feature is not available in open-source Vespa.");
        }
    }
Validates that 'access-control' is not enabled when no access control filter implementation is available.

@author bjorncs
config-model/src/main/java/com/yahoo/vespa/model/application/validation/AccessControlFilterValidator.java