private UpstreamInstance getClusterLastUpdateInstance(final List<UpstreamInstance> allInstances) {
        if (CollectionUtils.isEmpty(allInstances)) {
            return null;
        }
        return allInstances.stream()
                .filter(Objects::nonNull)
                .filter(UpstreamInstance::isHealthy)
                .max(Comparator.comparing(UpstreamInstance::getStartupTime))
                .orElse(null);
    }
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