If you have a driver, filter says sync an attr bidirectionally. Merge
authority is Default, and the attributes in the Application and Identity
Vault are both single valued.

Both sides have values, but they differ. And a merge happens.

What happens to the data?

Docs are unclear and I am unsure what happens.

My guess is that the source of the merge event wins. I.e. If merge
event is on Sub channel, the value from the IDV is written to the
application and vica versa.

Any thoughts?