Revit API Fun: FamilyManager.SetFormula() Needs Transaction But FamilyManager.AddParameter() Does Not!

Based on our experiences in the past decades, it’s fun to play with Revit API. Here is one.

The method FamDoc.FamilyManager.SetFormula(…) needs a transaction, otherwise:

'A sub-transaction can only be active inside an open Transaction.'

But FamDoc.FamilyManager.AddParameter(…) does not! It should have started one inside itself.