remove empty timeouts blocks in copyTimeoutValues

The hcl2shims will always add in the timeouts block, because there's no
way to differentiate a null single block from an empty one in the
flatmapped state. Since we are only concerned with keeping the prior
timeouts value, always set the new value to null, and then copy over the
prior value if it exists.

helper/plugin/grpc_provider.go

@@ -1125,22 +1125,34 @@ func normalizeFlatmapContainers(prior map[string]string, attrs map[string]string
 // the Private/Meta fields. we need to copy those values into the planned state
 // so that core doesn't see a perpetual diff with the timeout block.
 func copyTimeoutValues(to cty.Value, from cty.Value) cty.Value {
-	// if `from` is null, then there are no attributes, and if `to` is null we
-	// are planning to remove it altogether.
-	if from.IsNull() || to.IsNull() {
+	// if `to` is null we are planning to remove it altogether.
+	if to.IsNull() {
 		return to
 	}
+	toAttrs := to.AsValueMap()
+	// We need to remove the key since the hcl2shims will add a non-null block
+	// because we can't determine if a single block was null from the flatmapped
+	// values. This needs to conform to the correct schema for marshaling, so
+	// change the value to null rather than deleting it from the object map.
+	timeouts, ok := toAttrs[schema.TimeoutsConfigKey]
+	if ok {
+		toAttrs[schema.TimeoutsConfigKey] = cty.NullVal(timeouts.Type())
+	}
+
+	// if from is null then there are no timeouts to copy
+	if from.IsNull() {
+		return cty.ObjectVal(toAttrs)
+	}
 
 	fromAttrs := from.AsValueMap()
-	timeouts, ok := fromAttrs[schema.TimeoutsConfigKey]
+	timeouts, ok = fromAttrs[schema.TimeoutsConfigKey]
 
-	// no timeouts to copy
-	// timeouts shouldn't be unknown, but don't copy possibly invalid values
+	// timeouts shouldn't be unknown, but don't copy possibly invalid values either
 	if !ok || timeouts.IsNull() || !timeouts.IsWhollyKnown() {
-		return to
+		// no timeouts block to copy
+		return cty.ObjectVal(toAttrs)
 	}
 
-	toAttrs := to.AsValueMap()
 	toAttrs[schema.TimeoutsConfigKey] = timeouts
 
 	return cty.ObjectVal(toAttrs)