chore: preserve original year

.kokoro/populate-secrets.sh

@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2021 Google LLC
+# Copyright 2020 Google LLC
 #
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file or at

.kokoro/release.sh

@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2021 Google LLC
+# Copyright 2020 Google LLC
 #
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file or at

.kokoro/trampoline.sh

@@ -1,17 +1,9 @@
 #!/bin/bash
-# Copyright 2017 Google Inc.
+# Copyright 2017 Google LLC
 #
-# 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.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
 
 set -eo pipefail
 

.kokoro/trampoline_v2.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# Copyright 2021 Google LLC
+# Copyright 2020 Google LLC
 #
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file or at

owlbot.py

@@ -28,8 +28,8 @@
 # with the BSD license expected in this repository
 s.replace(
     ".kokoro/**/*",
-    "# Copyright.*Google LLC.*# limitations under the License\.",
-    """# Copyright 2021 Google LLC
+    "# Copyright.*(\d{4}).*# limitations under the License\.",
+    """# Copyright \g<1> Google LLC
 #
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file or at