docs/plugin-protocol: Clarify use of GetMetadata (#37181)

* docs/plugin-protocol: Clarify use of GetMetadata

* Run `make protobuf`

---------

Co-authored-by: Sarah French <sarah.french@hashicorp.com>

docs/plugin-protocol/tfplugin5.proto

@@ -309,9 +309,9 @@ service Provider {
 
     // GetMetadata returns upfront information about server capabilities and
     // supported resource types without requiring the server to instantiate all
-    // schema information, which may be memory intensive. This RPC is optional,
-    // where clients may receive an unimplemented RPC error. Clients should
-    // ignore the error and call the GetSchema RPC as a fallback.
+    // schema information, which may be memory intensive.
+    // This method is CURRENTLY UNUSED and it serves mostly for convenience
+    // of code generation inside of terraform-plugin-mux.
     rpc GetMetadata(GetMetadata.Request) returns (GetMetadata.Response);
 
     // GetSchema returns schema information for the provider, data resources,

docs/plugin-protocol/tfplugin6.proto

@@ -328,9 +328,9 @@ service Provider {
 
     // GetMetadata returns upfront information about server capabilities and
     // supported resource types without requiring the server to instantiate all
-    // schema information, which may be memory intensive. This RPC is optional,
-    // where clients may receive an unimplemented RPC error. Clients should
-    // ignore the error and call the GetProviderSchema RPC as a fallback.
+    // schema information, which may be memory intensive.
+    // This method is CURRENTLY UNUSED and it serves mostly for convenience
+    // of code generation inside of terraform-plugin-mux.
     rpc GetMetadata(GetMetadata.Request) returns (GetMetadata.Response);
 
     // GetSchema returns schema information for the provider, data resources,

internal/tfplugin5/tfplugin5.pb.go

@@ -7554,9 +7554,9 @@ const _ = grpc.SupportPackageIsVersion6
 type ProviderClient interface {
 	// GetMetadata returns upfront information about server capabilities and
 	// supported resource types without requiring the server to instantiate all
-	// schema information, which may be memory intensive. This RPC is optional,
-	// where clients may receive an unimplemented RPC error. Clients should
-	// ignore the error and call the GetSchema RPC as a fallback.
+	// schema information, which may be memory intensive.
+	// This method is CURRENTLY UNUSED and it serves mostly for convenience
+	// of code generation inside of terraform-plugin-mux.
 	GetMetadata(ctx context.Context, in *GetMetadata_Request, opts ...grpc.CallOption) (*GetMetadata_Response, error)
 	// GetSchema returns schema information for the provider, data resources,
 	// and managed resources.
@@ -7847,9 +7847,9 @@ func (c *providerClient) Stop(ctx context.Context, in *Stop_Request, opts ...grp
 type ProviderServer interface {
 	// GetMetadata returns upfront information about server capabilities and
 	// supported resource types without requiring the server to instantiate all
-	// schema information, which may be memory intensive. This RPC is optional,
-	// where clients may receive an unimplemented RPC error. Clients should
-	// ignore the error and call the GetSchema RPC as a fallback.
+	// schema information, which may be memory intensive.
+	// This method is CURRENTLY UNUSED and it serves mostly for convenience
+	// of code generation inside of terraform-plugin-mux.
 	GetMetadata(context.Context, *GetMetadata_Request) (*GetMetadata_Response, error)
 	// GetSchema returns schema information for the provider, data resources,
 	// and managed resources.

internal/tfplugin6/tfplugin6.pb.go

@@ -7237,9 +7237,9 @@ const _ = grpc.SupportPackageIsVersion6
 type ProviderClient interface {
 	// GetMetadata returns upfront information about server capabilities and
 	// supported resource types without requiring the server to instantiate all
-	// schema information, which may be memory intensive. This RPC is optional,
-	// where clients may receive an unimplemented RPC error. Clients should
-	// ignore the error and call the GetProviderSchema RPC as a fallback.
+	// schema information, which may be memory intensive.
+	// This method is CURRENTLY UNUSED and it serves mostly for convenience
+	// of code generation inside of terraform-plugin-mux.
 	GetMetadata(ctx context.Context, in *GetMetadata_Request, opts ...grpc.CallOption) (*GetMetadata_Response, error)
 	// GetSchema returns schema information for the provider, data resources,
 	// and managed resources.
@@ -7530,9 +7530,9 @@ func (c *providerClient) StopProvider(ctx context.Context, in *StopProvider_Requ
 type ProviderServer interface {
 	// GetMetadata returns upfront information about server capabilities and
 	// supported resource types without requiring the server to instantiate all
-	// schema information, which may be memory intensive. This RPC is optional,
-	// where clients may receive an unimplemented RPC error. Clients should
-	// ignore the error and call the GetProviderSchema RPC as a fallback.
+	// schema information, which may be memory intensive.
+	// This method is CURRENTLY UNUSED and it serves mostly for convenience
+	// of code generation inside of terraform-plugin-mux.
 	GetMetadata(context.Context, *GetMetadata_Request) (*GetMetadata_Response, error)
 	// GetSchema returns schema information for the provider, data resources,
 	// and managed resources.