[miele] Miele XGW 3000 gateway continuously removed from and readded to inbox

[jlaur]

The mDNS discovery removed the Miele XGW 3000 gateway from the inbox every two minutes and shortly after adds it again:

2021-12-21 16:50:19.479 [INFO ] [openhab.event.InboxRemovedEvent     ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been removed.
2021-12-21 16:50:21.918 [INFO ] [g.discovery.internal.PersistentInbox] - Added new thing 'miele:xgw3000:Miele_XGW3000' to inbox.
2021-12-21 16:50:21.919 [INFO ] [openhab.event.InboxAddedEvent       ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been added.
2021-12-21 16:52:19.512 [INFO ] [openhab.event.InboxRemovedEvent     ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been removed.
2021-12-21 16:52:21.757 [INFO ] [openhab.event.InboxAddedEvent       ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been added.
2021-12-21 16:52:21.757 [INFO ] [g.discovery.internal.PersistentInbox] - Added new thing 'miele:xgw3000:Miele_XGW3000' to inbox.
2021-12-21 16:54:19.502 [INFO ] [openhab.event.InboxRemovedEvent     ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been removed.
2021-12-21 16:54:21.632 [INFO ] [openhab.event.InboxAddedEvent       ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been added.
2021-12-21 16:54:21.632 [INFO ] [g.discovery.internal.PersistentInbox] - Added new thing 'miele:xgw3000:Miele_XGW3000' to inbox.
2021-12-21 16:56:19.498 [INFO ] [openhab.event.InboxRemovedEvent     ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been removed.
2021-12-21 16:56:21.882 [INFO ] [openhab.event.InboxAddedEvent       ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been added.
2021-12-21 16:56:21.882 [INFO ] [g.discovery.internal.PersistentInbox] - Added new thing 'miele:xgw3000:Miele_XGW3000' to inbox.
2021-12-21 16:58:19.515 [INFO ] [openhab.event.InboxRemovedEvent     ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been removed.
2021-12-21 16:58:21.825 [INFO ] [openhab.event.InboxAddedEvent       ] - Discovery Result with UID 'miele:xgw3000:Miele_XGW3000' has been added.
2021-12-21 16:58:21.824 [INFO ] [g.discovery.internal.PersistentInbox] - Added new thing 'miele:xgw3000:Miele_XGW3000' to inbox.

Expected Behavior

If the gateway disappears for a few seconds, it doesn't make sense to remove it from the inbox immediately.

Current Behavior

The gateway is removed and rediscovered every two minutes.

Possible Solution

Like the fix in openhab/openhab-core#2144 for UPnP, this could be extended to mDNS to work the same way, allowing implementations of MDNSDiscoveryParticipant to announce a desired grace period. @andrewfg has already prepared openhab/openhab-core#2635 for supporting this in core, and also provided #11834 for consuming it in the Miele binding.

Steps to Reproduce

Install the Miele binding while having an XGW 3000 gateway on the same network as the openHAB system.