Thanks to @stephen_nutt I do now. It's one of @iharyadi's environmental sensor that I've added a relay to and "attribute (BinaryOutput)" now makes sense. Thanks to both of you for helping me find this.
Exactly, and now that I know where to look I could do that BUT that device is referenced only twice in NR, once to read "Illuminance" and once to send a "refresh". The only place the relay is referenced is in a Virtual Switch I setup in HE and the VS is only by a tile on the [RELEASE] HD+ - Android Dashboard which is via Maker API so now I'm at a loss to understand how the BinaryOutput attribute is even known to NR.
EDIT: I searched the flows_host.json file for several terms related to the device and the only thing I find in there is the ID of 834. There is no "binary" anything so I I need @fblackburn to help sort this out.
Another odd thing is that the header on the debug message I posted above cites the "websocket" config while I only use webhook in the 2 nodes that reference device 834 in NR.