fix： 设备一直不上线就判断为离线

snowy-plugin/snowy-plugin-coldchain/src/main/java/vip/xiaonuo/coldchain/core/alarm/offline/DeviceOfflineDetectionService.java

@@ -106,7 +106,7 @@ public class DeviceOfflineDetectionService {
                     monitorTargetService.updateStatusByDeviceCode(deviceCode, route, MonitorStatusEnum.ONLINE);
                 }
             } else {
-                // 如果设备上报时间为空，认为设备可能从未上报过数据
+                monitorTargetService.updateStatusByDeviceCode(deviceCode, route, MonitorStatusEnum.OFF);
                 log.info("设备 {}-{} 缺少数据，可能从未上报过。\n", deviceCode, route);
             }
         }