chore: update file headers (#515)

* changes without context

        autosynth cannot find the source of changes triggered by earlier changes in this
        repository, or by version upgrades to tools such as linters.

* chore: modify synth excludes

Co-authored-by: Bu Sun Kim <[email protected]>
Co-authored-by: Bu Sun Kim <[email protected]>
diff --git a/.kokoro/publish-docs.sh b/.kokoro/publish-docs.sh
index 0d97db8..0e5d978 100755
--- a/.kokoro/publish-docs.sh
+++ b/.kokoro/publish-docs.sh
@@ -1,4 +1,17 @@
 #!/bin/bash
+# Copyright 2020 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
+#
+#     https://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.
 
 set -eo pipefail
 
diff --git a/.kokoro/release.sh b/.kokoro/release.sh
index cf85555..ded1bae 100755
--- a/.kokoro/release.sh
+++ b/.kokoro/release.sh
@@ -1,4 +1,17 @@
 #!/bin/bash
+# Copyright 2020 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
+#
+#     https://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.
 
 set -eo pipefail
 
diff --git a/.kokoro/trampoline.sh b/.kokoro/trampoline.sh
index 4b4ba9f..e8c4251 100755
--- a/.kokoro/trampoline.sh
+++ b/.kokoro/trampoline.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2017 Google LLC
+# Copyright 2017 Google Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/synth.metadata b/synth.metadata
index ebfeb7f..0efbe1e 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -1,11 +1,17 @@
 {
-  "updateTime": "2019-09-12T22:40:28.148018Z",
   "sources": [
     {
-      "template": {
-        "name": "python_library",
-        "origin": "synthtool.gcp",
-        "version": "2019.5.2"
+      "git": {
+        "name": ".",
+        "remote": "[email protected]:googleapis/google-auth-library-python",
+        "sha": "aab4f2fdb2cfa598397026865ccb270a05c38cc4"
+      }
+    },
+    {
+      "git": {
+        "name": "synthtool",
+        "remote": "https://github.com/googleapis/synthtool.git",
+        "sha": "71b8a272549c06b5768d00fa48d3ae990e871bec"
       }
     }
   ]
diff --git a/synth.py b/synth.py
index 069b214..49bf2dd 100644
--- a/synth.py
+++ b/synth.py
@@ -7,4 +7,11 @@
 # Add templated files
 # ----------------------------------------------------------------------------
 templated_files = common.py_library(unit_cov_level=100, cov_level=100)
-s.move(templated_files / '.kokoro')  # just move kokoro configs
\ No newline at end of file
+s.move(
+    templated_files / ".kokoro",
+    excludes=[
+        ".kokoro/continuous/common.cfg",
+        ".kokoro/presubmit/common.cfg",
+        ".kokoro/build.sh",
+    ],
+)  # just move kokoro configs