* Checks whether the specified instance is currently active.
     *
     * @param targetInstanceId the instance ID to check.
     * @return {@code true} if the instance is active.
     */
    public boolean isInstanceActive(final String targetInstanceId) {
        return getActiveInstances().stream().anyMatch(i -> i.instanceId.equals(targetInstanceId));
    }

      },
      "hostname": {
        "type": "keyword"
      },
      "name": {
        "type": "keyword"
      },
      "status": {
        "type": "keyword"
      },
      "targetInstanceId": {
        "type": "keyword"
      },
      "data": {
        "type": "text",
        "index": false
      },
      "createdTime": {
        "type": "long"
      },
      "expiredTime": {

                + "\"targetInstanceId\":\"*\",\"createdTime\":5000}},"
                + "{\"_source\":{\"type\":\"event\",\"name\":\"e2\",\"instanceId\":\"node3\","
                + "\"targetInstanceId\":\"*\",\"createdTime\":7000}},"
                + "{\"_source\":{\"type\":\"event\",\"name\":\"e3\",\"instanceId\":\"node4\","
                + "\"targetInstanceId\":\"*\",\"createdTime\":6000}}" + "]}}";