google_google_service_account_key data source has a project argument that appears to be unused

[SarahFrench]

The google_google_service_account_key data source has a project argument that appears to be unused:

terraform-provider-google/google/services/resourcemanager/data_source_google_service_account_key.go

Lines 34 to 37 in efe355c

	"project": {
	Type: schema.TypeString,
	Optional: true,
	},

If you search that file for "project" you'll see that there are no d.Get("project"), d.Set("project",...), or tpgresource.GetProject(d, config) calls in the Read method, so the value isn't set in the data source's data, let alone used while making the GET request for the SA key.

It looks like the project input was used in the past, but the Read method was updated over time while the schema stayed the same:?