Reference: https://github.com/hashicorp/terraform/issues/30373
This change forward ports the `legacy_type_system` boolean fields in the `ApplyResourceChange.Response` and `PlanResourceChange.Response` messages that existed in protocol version 5, so that existing terraform-plugin-sdk/v2 providers can be muxed with protocol version 6 providers (e.g. terraform-plugin-framework) while also taking advantage of the newer protocol features. This functionality should not be used by any providers or SDKs except those built with terraform-plugin-sdk.
Updated via:
```shell
cp docs/plugin-protocol/tfplugin6.1.proto docs/plugin-protocol/tfplugin6.2.proto
# Copy legacy_type_system fields from tfplugin5.2.proto into ApplyResourceChange.Response and PlanResourceChange
rm internal/tfplugin6/tfplugin6.proto
ln -s ../../docs/plugin-protocol/tfplugin6.2.proto internal/tfplugin6/tfplugin6.proto
go run tools/protobuf-compile/protobuf-compile.go `pwd`
# Updates to internal/plugin6/grpc_provider.go
```
Minor version increase to deprecate min_items and max_items in nested
types.
Nested types have MinItems and MaxItems fields that were inherited from
the block implementation, but were never validated by Terraform, and are
not supported by the HCL decoder validations. Mark these fields as
deprecated, indicating that the SDK should handle the required
validation.
This is the first commit for plugin protocol v6. This is currently
unused (dead) code; future commits will add the necessary conversion
packages, extend configschema, and modify the providers.Interface.
The new plugin protocol includes the following changes:
- A new field has been added to Attribute: NestedType. This will be the
key new feature in plugin protocol v6
- Several massages were renamed for consistency with the verb-noun
pattern seen in _most_ messages.
- The prepared_config has been removed from PrepareProviderConfig
(renamed ValidateProviderConfig), as it has never been used.
- The provisioner service has been removed entirely. This has no impact
on built-in provisioners. 3rd party provisioners are not supported by
the SDK and are not included in this protocol at all.
