private UpstreamInstance getClusterLastUpdateInstance(final SelectorVO selectorVO) {
        List<UpstreamInstance> allInstances = getInstances(selectorVO.getId(), selectorVO.getName(), selectorVO.getEnabled());
        if (CollectionUtils.isEmpty(allInstances)) {
            return null;
        }
        return getClusterLastUpdateInstance(allInstances);
    }
Get the last started healthy instance of each cluster.

@return List
shenyu-admin/src/main/java/org/apache/shenyu/admin/service/manager/impl/LoadServiceDocEntryImpl.java