This ensures that when we hook this into the main diff logic, that we
can just re-diff the keys that are modified, ensuring that the diff is
not re-run on keys that were not touched, or on keys that were
intentionally removed.
This folder contains helper libraries for Terraform plugins. A running
joke is that this is "Terraform standard library" for plugins. The goal
of the packages in this directory are to provide high-level helpers to
make it easier to implement the various aspects of writing a plugin for
Terraform.