This provider uses the lang package directly, which is an internal package in terraform-plugin-sdk, and can thus not be migrated.
[lorbus@localhost terraform-provider-template]$ tf-sdk-migrator check
Checking Go runtime version ...
Go version 1.13.5: OK.
Checking whether provider uses Go modules...
Go modules in use: OK.
Checking version of github.com/hashicorp/terraform-plugin-sdk to determine if provider was already migrated...
Checking version of github.com/hashicorp/terraform used in provider...
Terraform version does not satisfy constraint >=0.12.7. Found Terraform version: 0.12.0-alpha4.0.20190424121927-9327eedb0417
Checking whether provider uses deprecated SDK packages or identifiers...
Deprecated SDK packages in use:
* github.com/hashicorp/terraform/lang
Some constraints not satisfied. Please resolve these before migrating to the new SDK.
This provider uses the
lang
package directly, which is an internal package interraform-plugin-sdk
, and can thus not be migrated.