Best to have a test of a left-nested Map.
Since Products nest on the outer side, the depth only goes up by one.
Rename some fields in anticipation of making this more general.
Rename the class, but still with ancestor behavior only.
Rename the IT, too.
Update other test, too.
Add the extra rows from BranchLookup_DefaultIT before touching anything to make sure it'll be okay.
Allow descendants in input row types.
Remove a negative test that was checking against that.
Begin to add some of cursor.
Copy in a bunch of the BranchLookup tests.
Need to disable ones that cross to another branch.
Test filtering.
Update lookahead implementation.
Use new forms in optimizer.
Remove old IT.
Update GI maintenance.
Change SERIAL back to BY DEFAULT
Update JSON plan generator.
Fix comment.
Update a couple more.
Use a supported method.