Remove gogoproto.stdtime

This commit removes gogoproto.stdtime, since it is not supported by
Google's official toolchain
(see https://github.com/containerd/containerd/issues/6564).

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

protobuf/timestamp.go

@@ -0,0 +1,48 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package protobuf
+
+import (
+	"time"
+
+	"github.com/gogo/protobuf/types"
+)
+
+// Once we migrate off from gogo/protobuf, we can use the function below, which don't return any errors.
+// https://github.com/protocolbuffers/protobuf-go/blob/v1.28.0/types/known/timestamppb/timestamp.pb.go#L200-L208
+
+// ToTimestamp creates protobuf's Timestamp from time.Time.
+func ToTimestamp(from time.Time) *types.Timestamp {
+	pt, err := types.TimestampProto(from)
+	if err != nil {
+		panic(err)
+	}
+	return pt
+}
+
+// FromTimestamp creates time.Time from protobuf's Timestamp.
+func FromTimestamp(from *types.Timestamp) time.Time {
+	if from == nil {
+		// Return time.Time's zero value as like timestamppb.
+		return time.Time{}.UTC()
+	}
+	tt, err := types.TimestampFromProto(from)
+	if err != nil {
+		panic(err)
+	}
+	return tt
+}