I forgot to add `Computed: true` when I made the "key_name" field
optional in #1751.
This made the behavior:
* Name generated in Create and set as ID
* Follow up plan (without refresh) was nice and empty
* During refresh, name gets cleared out on Read, causing a bad diff on
subsequent plans
We can automatically catch bugs like this if we add yet another
verification step to our resource acceptance tests -> a post
Refresh+Plan that we verify is empty.
I left the non-refresh Plan verification in, because it's important that
_both_ of these are empty after an Apply.
149e52ad1f