This provides a deep copy of a schemaMap, which will be needed for the
diff customization process as ResourceDiff will be able to flag fields
as ForceNew - we don't want to affect the source schema.
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.