private void processGlobalDefaultBackend(final ShenyuMemoryConfig shenyuMemoryConfig, final V1Ingress v1Ingress, final String pluginName) {
        Pair<Pair<String, String>, IngressConfiguration> configurationPair = shenyuMemoryConfig.getGlobalDefaultBackend();
        if (Objects.nonNull(configurationPair)) {
            synchronized (IngressReconciler.class) {
                if (Objects.isNull(globalDefaultBackend)) {
                    // Add a default backend
                    IngressConfiguration ingressConfiguration = configurationPair.getRight();
                    SelectorData selectorData = ingressConfiguration.getSelectorData();
                    shenyuCacheRepository.saveOrUpdateSelectorData(selectorData);
                    ingressConfiguration.getRuleDataList().forEach(shenyuCacheRepository::saveOrUpdateRuleData);
                    ingressConfiguration.getMetaDataList().forEach(shenyuCacheRepository::saveOrUpdateMetaData);
                    globalDefaultBackend = configurationPair;
                    IngressSelectorCache.getInstance().put(
                            Objects.requireNonNull(v1Ingress.getMetadata()).getNamespace(),
                            v1Ingress.getMetadata().getName(),
                            pluginName,
                            selectorData.getId()
                    );
                }
            }
        }
    }
Check whether the IngressClass is shenyu, check the annotation first.

@param v1Ingress v1Ingress
@return boolean
shenyu-kubernetes-controller/src/main/java/org/apache/shenyu/k8s/reconciler/IngressReconciler.java