tfprotov5+tfprotov6: Add GetProviderSchemaOptional server capability

Reference: #310

.changes/unreleased/ENHANCEMENTS-20230707-100231.yaml

@@ -0,0 +1,7 @@
+kind: ENHANCEMENTS
+body: 'tfprotov5: Added `ServerCapabilities` type `GetProviderSchemaOptional` field,
+  which when enabled can signal that the provider supports RPC operations without
+  the `GetProviderSchema` RPC being called first'
+time: 2023-07-07T10:02:31.242394-04:00
+custom:
+  Issue: "310"

.changes/unreleased/ENHANCEMENTS-20230707-100339.yaml

@@ -0,0 +1,7 @@
+kind: ENHANCEMENTS
+body: 'tfprotov6: Added `ServerCapabilities` type `GetProviderSchemaOptional` field,
+  which when enabled can signal that the provider supports RPC operations without
+  the `GetProviderSchema` RPC being called first'
+time: 2023-07-07T10:03:39.802189-04:00
+custom:
+  Issue: "310"

tfprotov5/internal/tfplugin5/tfplugin5.proto

@@ -1,9 +1,9 @@
 // Copyright (c) HashiCorp, Inc.
 // SPDX-License-Identifier: MPL-2.0
 
-// Terraform Plugin RPC protocol version 5.3
+// Terraform Plugin RPC protocol version 5.4
 //
-// This file defines version 5.3 of the RPC protocol. To implement a plugin
+// This file defines version 5.4 of the RPC protocol. To implement a plugin
 // against this protocol, copy this definition into your own codebase and
 // use protoc to generate stubs for your target language.
 //
@@ -172,6 +172,12 @@ message GetProviderSchema {
         // The plan_destroy capability signals that a provider expects a call
         // to PlanResourceChange when a resource is going to be destroyed.
         bool plan_destroy = 1;
+
+        // The get_provider_schema_optional capability indicates that this
+        // provider does not require calling GetProviderSchema to operate
+        // normally, and the caller can used a cached copy of the provider's
+        // schema.
+        bool get_provider_schema_optional = 2;
     }
 }
 

tfprotov5/internal/toproto/server_capabilities.go

@@ -14,6 +14,7 @@ func GetProviderSchema_ServerCapabilities(in *tfprotov5.ServerCapabilities) *tfp
 	}
 
 	return &tfplugin5.GetProviderSchema_ServerCapabilities{
-		PlanDestroy: in.PlanDestroy,
+		GetProviderSchemaOptional: in.GetProviderSchemaOptional,
+		PlanDestroy:               in.PlanDestroy,
 	}
 }

tfprotov5/server_capabilities.go

@@ -14,4 +14,9 @@ type ServerCapabilities struct {
 	// opt-in to prevent unexpected errors or panics since the
 	// ProposedNewState in PlanResourceChangeRequest will be a null value.
 	PlanDestroy bool
+
+	// GetProviderSchemaOptional signals that this provider does not require
+	// having the GetProviderSchema RPC called first to operate normally. This
+	// means the caller can use a cached copy of the provider's schema instead.
+	GetProviderSchemaOptional bool
 }

tfprotov6/internal/tfplugin6/tfplugin6.proto

@@ -1,9 +1,9 @@
 // Copyright (c) HashiCorp, Inc.
 // SPDX-License-Identifier: MPL-2.0
 
-// Terraform Plugin RPC protocol version 6.3
+// Terraform Plugin RPC protocol version 6.4
 //
-// This file defines version 6.3 of the RPC protocol. To implement a plugin
+// This file defines version 6.4 of the RPC protocol. To implement a plugin
 // against this protocol, copy this definition into your own codebase and
 // use protoc to generate stubs for your target language.
 //
@@ -191,6 +191,12 @@ message GetProviderSchema {
         // The plan_destroy capability signals that a provider expects a call
         // to PlanResourceChange when a resource is going to be destroyed.
         bool plan_destroy = 1;
+
+        // The get_provider_schema_optional capability indicates that this
+        // provider does not require calling GetProviderSchema to operate
+        // normally, and the caller can used a cached copy of the provider's
+        // schema.
+        bool get_provider_schema_optional = 2;
     }
 }
 

tfprotov6/internal/toproto/server_capabilities.go

@@ -14,6 +14,7 @@ func GetProviderSchema_ServerCapabilities(in *tfprotov6.ServerCapabilities) *tfp
 	}
 
 	return &tfplugin6.GetProviderSchema_ServerCapabilities{
-		PlanDestroy: in.PlanDestroy,
+		GetProviderSchemaOptional: in.GetProviderSchemaOptional,
+		PlanDestroy:               in.PlanDestroy,
 	}
 }

tfprotov6/server_capabilities.go

@@ -9,6 +9,11 @@ package tfprotov6
 // This information is used in GetProviderSchemaResponse as capabilities are
 // static features which must be known upfront in the provider server.
 type ServerCapabilities struct {
+	// GetProviderSchemaOptional signals that this provider does not require
+	// having the GetProviderSchema RPC called first to operate normally. This
+	// means the caller can use a cached copy of the provider's schema instead.
+	GetProviderSchemaOptional bool
+
 	// PlanDestroy signals that a provider expects a call to
 	// PlanResourceChange when a resource is going to be destroyed. This is
 	// opt-in to prevent unexpected errors or panics since the