public TThrottleQuotaResp getThrottleQuota() {
    TThrottleQuotaResp throttleQuotaResp = new TThrottleQuotaResp();
    if (!quotaInfo.getThrottleQuotaLimit().isEmpty()) {
      throttleQuotaResp.setThrottleQuota(quotaInfo.getThrottleQuotaLimit());
    }
    throttleQuotaResp.setStatus(RpcUtils.getStatus(TSStatusCode.SUCCESS_STATUS));
    return throttleQuotaResp;
  }
If the new quota is smaller than the quota already used, the setting fails.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/ClusterQuotaManager.java