Add comments describing unimplemented server fields

Author: travisyx

pkg/gce-pd-csi-driver/controller.go

@@ -109,6 +109,8 @@ type GCEControllerServer struct {
 
 	listVolumesConfig ListVolumesConfig
 
+	// Embed UnimplementedControllerServer to ensure the driver returns Unimplemented for any
+	// new RPC methods that might be introduced in future versions of the spec.
 	csi.UnimplementedControllerServer
 }
 

pkg/gce-pd-csi-driver/identity.go

@@ -25,6 +25,8 @@ import (
 type GCEIdentityServer struct {
 	Driver *GCEDriver
 
+	// Embed UnimplementedIdentityServer to ensure the driver returns Unimplemented for any
+	// new RPC methods that might be introduced in future versions of the spec.
 	csi.UnimplementedIdentityServer
 }
 

pkg/gce-pd-csi-driver/node.go

@@ -60,6 +60,8 @@ type GCENodeServer struct {
 	formatAndMountSemaphore chan any
 	formatAndMountTimeout   time.Duration
 
+	// Embed UnimplementedNodeServer to ensure the driver returns Unimplemented for any
+	// new RPC methods that might be introduced in future versions of the spec.
 	csi.UnimplementedNodeServer
 }