diff --git a/.github/header-checker-lint.yml b/.github/header-checker-lint.yml
new file mode 100644
index 0000000..fc281c0
--- /dev/null
+++ b/.github/header-checker-lint.yml
@@ -0,0 +1,15 @@
+{"allowedCopyrightHolders": ["Google LLC"],
+ "allowedLicenses": ["Apache-2.0", "MIT", "BSD-3"],
+ "ignoreFiles": ["**/requirements.txt", "**/requirements-test.txt"],
+ "sourceFileExtensions": [
+ 	"ts", 
+ 	"js", 
+ 	"java", 
+ 	"sh", 
+ 	"Dockerfile", 
+ 	"yaml", 
+ 	"py",
+ 	"html",
+ 	"txt"
+ ]
+}
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index b9daa52..b4243ce 100644
--- a/.gitignore
+++ b/.gitignore
@@ -50,8 +50,10 @@ docs.metadata
 
 # Virtual environment
 env/
+
+# Test logs
 coverage.xml
-sponge_log.xml
+*sponge_log.xml
 
 # System test environment variables.
 system_tests/local_test_setup
diff --git a/.kokoro/build.sh b/.kokoro/build.sh
index 078993e..2917e86 100755
--- a/.kokoro/build.sh
+++ b/.kokoro/build.sh
@@ -15,7 +15,11 @@
 
 set -eo pipefail
 
-cd github/python-iam
+if [[ -z "${PROJECT_ROOT:-}" ]]; then
+    PROJECT_ROOT="github/python-iam"
+fi
+
+cd "${PROJECT_ROOT}"
 
 # Disable buffering, so that the logs stream through.
 export PYTHONUNBUFFERED=1
@@ -30,16 +34,26 @@ export GOOGLE_APPLICATION_CREDENTIALS=${KOKORO_GFILE_DIR}/service-account.json
 export PROJECT_ID=$(cat "${KOKORO_GFILE_DIR}/project-id.json")
 
 # Remove old nox
-python3.6 -m pip uninstall --yes --quiet nox-automation
+python3 -m pip uninstall --yes --quiet nox-automation
 
 # Install nox
-python3.6 -m pip install --upgrade --quiet nox
-python3.6 -m nox --version
+python3 -m pip install --upgrade --quiet nox
+python3 -m nox --version
+
+# If this is a continuous build, send the test log to the FlakyBot.
+# See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"continuous"* ]]; then
+  cleanup() {
+    chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
+    $KOKORO_GFILE_DIR/linux_amd64/flakybot
+  }
+  trap cleanup EXIT HUP
+fi
 
 # If NOX_SESSION is set, it only runs the specified session,
 # otherwise run all the sessions.
 if [[ -n "${NOX_SESSION:-}" ]]; then
-    python3.6 -m nox -s "${NOX_SESSION:-}"
+    python3 -m nox -s ${NOX_SESSION:-}
 else
-    python3.6 -m nox
+    python3 -m nox
 fi
diff --git a/.kokoro/docs/docs-presubmit.cfg b/.kokoro/docs/docs-presubmit.cfg
index 1118107..06816ca 100644
--- a/.kokoro/docs/docs-presubmit.cfg
+++ b/.kokoro/docs/docs-presubmit.cfg
@@ -15,3 +15,14 @@ env_vars: {
     key: "TRAMPOLINE_IMAGE_UPLOAD"
     value: "false"
 }
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-iam/.kokoro/build.sh"
+}
+
+# Only run this nox session.
+env_vars: {
+    key: "NOX_SESSION"
+    value: "docs docfx"
+}
diff --git a/.kokoro/samples/python3.6/periodic-head.cfg b/.kokoro/samples/python3.6/periodic-head.cfg
new file mode 100644
index 0000000..f9cfcd3
--- /dev/null
+++ b/.kokoro/samples/python3.6/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.7/periodic-head.cfg b/.kokoro/samples/python3.7/periodic-head.cfg
new file mode 100644
index 0000000..f9cfcd3
--- /dev/null
+++ b/.kokoro/samples/python3.7/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.8/periodic-head.cfg b/.kokoro/samples/python3.8/periodic-head.cfg
new file mode 100644
index 0000000..f9cfcd3
--- /dev/null
+++ b/.kokoro/samples/python3.8/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/test-samples-against-head.sh b/.kokoro/test-samples-against-head.sh
new file mode 100755
index 0000000..1f371d6
--- /dev/null
+++ b/.kokoro/test-samples-against-head.sh
@@ -0,0 +1,28 @@
+#!/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.
+
+# A customized test runner for samples.
+#
+# For periodic builds, you can specify this file for testing against head.
+
+# `-e` enables the script to automatically fail when a command fails
+# `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
+set -eo pipefail
+# Enables `**` to include files nested inside sub-folders
+shopt -s globstar
+
+cd github/python-iam
+
+exec .kokoro/test-samples-impl.sh
diff --git a/.kokoro/test-samples-impl.sh b/.kokoro/test-samples-impl.sh
new file mode 100755
index 0000000..cf5de74
--- /dev/null
+++ b/.kokoro/test-samples-impl.sh
@@ -0,0 +1,102 @@
+#!/bin/bash
+# Copyright 2021 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.
+
+
+# `-e` enables the script to automatically fail when a command fails
+# `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
+set -eo pipefail
+# Enables `**` to include files nested inside sub-folders
+shopt -s globstar
+
+# Exit early if samples directory doesn't exist
+if [ ! -d "./samples" ]; then
+  echo "No tests run. `./samples` not found"
+  exit 0
+fi
+
+# Disable buffering, so that the logs stream through.
+export PYTHONUNBUFFERED=1
+
+# Debug: show build environment
+env | grep KOKORO
+
+# Install nox
+python3.6 -m pip install --upgrade --quiet nox
+
+# Use secrets acessor service account to get secrets
+if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
+    gcloud auth activate-service-account \
+	   --key-file="${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" \
+	   --project="cloud-devrel-kokoro-resources"
+fi
+
+# This script will create 3 files:
+# - testing/test-env.sh
+# - testing/service-account.json
+# - testing/client-secrets.json
+./scripts/decrypt-secrets.sh
+
+source ./testing/test-env.sh
+export GOOGLE_APPLICATION_CREDENTIALS=$(pwd)/testing/service-account.json
+
+# For cloud-run session, we activate the service account for gcloud sdk.
+gcloud auth activate-service-account \
+       --key-file "${GOOGLE_APPLICATION_CREDENTIALS}"
+
+export GOOGLE_CLIENT_SECRETS=$(pwd)/testing/client-secrets.json
+
+echo -e "\n******************** TESTING PROJECTS ********************"
+
+# Switch to 'fail at end' to allow all tests to complete before exiting.
+set +e
+# Use RTN to return a non-zero value if the test fails.
+RTN=0
+ROOT=$(pwd)
+# Find all requirements.txt in the samples directory (may break on whitespace).
+for file in samples/**/requirements.txt; do
+    cd "$ROOT"
+    # Navigate to the project folder.
+    file=$(dirname "$file")
+    cd "$file"
+
+    echo "------------------------------------------------------------"
+    echo "- testing $file"
+    echo "------------------------------------------------------------"
+
+    # Use nox to execute the tests for the project.
+    python3.6 -m nox -s "$RUN_TESTS_SESSION"
+    EXIT=$?
+
+    # If this is a periodic build, send the test log to the FlakyBot.
+    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+    if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
+      chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
+      $KOKORO_GFILE_DIR/linux_amd64/flakybot
+    fi
+
+    if [[ $EXIT -ne 0 ]]; then
+      RTN=1
+      echo -e "\n Testing failed: Nox returned a non-zero exit code. \n"
+    else
+      echo -e "\n Testing completed.\n"
+    fi
+
+done
+cd "$ROOT"
+
+# Workaround for Kokoro permissions issue: delete secrets
+rm testing/{test-env.sh,client-secrets.json,service-account.json}
+
+exit "$RTN"
diff --git a/.kokoro/test-samples.sh b/.kokoro/test-samples.sh
index 77146e0..f9c337d 100755
--- a/.kokoro/test-samples.sh
+++ b/.kokoro/test-samples.sh
@@ -13,6 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# The default test runner for samples.
+#
+# For periodic builds, we rewinds the repo to the latest release, and
+# run test-samples-impl.sh.
 
 # `-e` enables the script to automatically fail when a command fails
 # `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
@@ -24,87 +28,19 @@ cd github/python-iam
 
 # Run periodic samples tests at latest release
 if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
+    # preserving the test runner implementation.
+    cp .kokoro/test-samples-impl.sh "${TMPDIR}/test-samples-impl.sh"
+    echo "--- IMPORTANT IMPORTANT IMPORTANT ---"
+    echo "Now we rewind the repo back to the latest release..."
     LATEST_RELEASE=$(git describe --abbrev=0 --tags)
     git checkout $LATEST_RELEASE
-fi
-
-# Exit early if samples directory doesn't exist
-if [ ! -d "./samples" ]; then
-  echo "No tests run. `./samples` not found"
-  exit 0
-fi
-
-# Disable buffering, so that the logs stream through.
-export PYTHONUNBUFFERED=1
-
-# Debug: show build environment
-env | grep KOKORO
-
-# Install nox
-python3.6 -m pip install --upgrade --quiet nox
-
-# Use secrets acessor service account to get secrets
-if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
-    gcloud auth activate-service-account \
-	   --key-file="${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" \
-	   --project="cloud-devrel-kokoro-resources"
-fi
-
-# This script will create 3 files:
-# - testing/test-env.sh
-# - testing/service-account.json
-# - testing/client-secrets.json
-./scripts/decrypt-secrets.sh
-
-source ./testing/test-env.sh
-export GOOGLE_APPLICATION_CREDENTIALS=$(pwd)/testing/service-account.json
-
-# For cloud-run session, we activate the service account for gcloud sdk.
-gcloud auth activate-service-account \
-       --key-file "${GOOGLE_APPLICATION_CREDENTIALS}"
-
-export GOOGLE_CLIENT_SECRETS=$(pwd)/testing/client-secrets.json
-
-echo -e "\n******************** TESTING PROJECTS ********************"
-
-# Switch to 'fail at end' to allow all tests to complete before exiting.
-set +e
-# Use RTN to return a non-zero value if the test fails.
-RTN=0
-ROOT=$(pwd)
-# Find all requirements.txt in the samples directory (may break on whitespace).
-for file in samples/**/requirements.txt; do
-    cd "$ROOT"
-    # Navigate to the project folder.
-    file=$(dirname "$file")
-    cd "$file"
-
-    echo "------------------------------------------------------------"
-    echo "- testing $file"
-    echo "------------------------------------------------------------"
-
-    # Use nox to execute the tests for the project.
-    python3.6 -m nox -s "$RUN_TESTS_SESSION"
-    EXIT=$?
-
-    # If this is a periodic build, send the test log to the Build Cop Bot.
-    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/buildcop.
-    if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
-      chmod +x $KOKORO_GFILE_DIR/linux_amd64/buildcop
-      $KOKORO_GFILE_DIR/linux_amd64/buildcop
+    echo "The current head is: "
+    echo $(git rev-parse --verify HEAD)
+    echo "--- IMPORTANT IMPORTANT IMPORTANT ---"
+    # move back the test runner implementation if there's no file.
+    if [ ! -f .kokoro/test-samples-impl.sh ]; then
+	cp "${TMPDIR}/test-samples-impl.sh" .kokoro/test-samples-impl.sh
     fi
+fi
 
-    if [[ $EXIT -ne 0 ]]; then
-      RTN=1
-      echo -e "\n Testing failed: Nox returned a non-zero exit code. \n"
-    else
-      echo -e "\n Testing completed.\n"
-    fi
-
-done
-cd "$ROOT"
-
-# Workaround for Kokoro permissions issue: delete secrets
-rm testing/{test-env.sh,client-secrets.json,service-account.json}
-
-exit "$RTN"
+exec .kokoro/test-samples-impl.sh
diff --git a/.kokoro/trampoline_v2.sh b/.kokoro/trampoline_v2.sh
index 719bcd5..4af6cdc 100755
--- a/.kokoro/trampoline_v2.sh
+++ b/.kokoro/trampoline_v2.sh
@@ -159,7 +159,7 @@ if [[ -n "${KOKORO_BUILD_ID:-}" ]]; then
 	"KOKORO_GITHUB_COMMIT"
 	"KOKORO_GITHUB_PULL_REQUEST_NUMBER"
 	"KOKORO_GITHUB_PULL_REQUEST_COMMIT"
-	# For Build Cop Bot
+	# For FlakyBot
 	"KOKORO_GITHUB_COMMIT_URL"
 	"KOKORO_GITHUB_PULL_REQUEST_URL"
     )
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a9024b1..32302e4 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -12,6 +12,6 @@ repos:
     hooks:
     - id: black
 -   repo: https://gitlab.com/pycqa/flake8
-    rev: 3.8.4
+    rev: 3.9.0
     hooks:
     - id: flake8
diff --git a/.trampolinerc b/.trampolinerc
index 995ee29..383b6ec 100644
--- a/.trampolinerc
+++ b/.trampolinerc
@@ -24,6 +24,7 @@ required_envvars+=(
 pass_down_envvars+=(
     "STAGING_BUCKET"
     "V2_STAGING_BUCKET"
+    "NOX_SESSION"
 )
 
 # Prevent unintentional override on the default image.
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 37b5e80..d952aed 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -70,9 +70,14 @@ We use `nox <https://nox.readthedocs.io/en/latest/>`__ to instrument our tests.
 - To test your changes, run unit tests with ``nox``::
 
     $ nox -s unit-2.7
-    $ nox -s unit-3.7
+    $ nox -s unit-3.8
     $ ...
 
+- Args to pytest can be passed through the nox command separated by a `--`. For
+  example, to run a single test::
+
+    $ nox -s unit-3.8 -- -k <name of test>
+
   .. note::
 
     The unit tests and system tests are described in the
@@ -93,8 +98,12 @@ On Debian/Ubuntu::
 ************
 Coding Style
 ************
+- We use the automatic code formatter ``black``. You can run it using
+  the nox session ``blacken``. This will eliminate many lint errors. Run via::
+
+   $ nox -s blacken
 
-- PEP8 compliance, with exceptions defined in the linter configuration.
+- PEP8 compliance is required, with exceptions defined in the linter configuration.
   If you have ``nox`` installed, you can test that you have not introduced
   any non-compliant code via::
 
@@ -133,13 +142,18 @@ Running System Tests
 
 - To run system tests, you can execute::
 
-   $ nox -s system-3.7
+   # Run all system tests
+   $ nox -s system-3.8
    $ nox -s system-2.7
 
+   # Run a single system test
+   $ nox -s system-3.8 -- -k <name of test>
+
+
   .. note::
 
       System tests are only configured to run under Python 2.7 and
-      Python 3.7. For expediency, we do not run them in older versions
+      Python 3.8. For expediency, we do not run them in older versions
       of Python 3.
 
   This alone will not run the tests. You'll need to change some local
diff --git a/MANIFEST.in b/MANIFEST.in
index e9e29d1..e783f4c 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -16,10 +16,10 @@
 
 # Generated by synthtool. DO NOT EDIT!
 include README.rst LICENSE
-recursive-include google *.json *.proto
+recursive-include google *.json *.proto py.typed
 recursive-include tests *
 global-exclude *.py[co]
 global-exclude __pycache__
 
 # Exclude scripts for samples readmegen
-prune scripts/readme-gen
\ No newline at end of file
+prune scripts/readme-gen
diff --git a/noxfile.py b/noxfile.py
index a4884a0..09285f4 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -18,6 +18,7 @@
 
 from __future__ import absolute_import
 import os
+import pathlib
 import shutil
 
 import nox
@@ -30,6 +31,22 @@
 SYSTEM_TEST_PYTHON_VERSIONS = ["3.8"]
 UNIT_TEST_PYTHON_VERSIONS = ["3.6", "3.7", "3.8", "3.9"]
 
+CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
+
+# 'docfx' is excluded since it only needs to run in 'docs-presubmit'
+nox.options.sessions = [
+    "unit",
+    "system",
+    "cover",
+    "lint",
+    "lint_setup_py",
+    "blacken",
+    "docs",
+]
+
+# Error if a python version is missing
+nox.options.error_on_missing_interpreters = True
+
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint(session):
@@ -70,17 +87,21 @@ def lint_setup_py(session):
 
 def default(session):
     # Install all test dependencies, then install this package in-place.
-    session.install("asyncmock", "pytest-asyncio")
 
-    session.install(
-        "mock", "pytest", "pytest-cov",
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
-    session.install("-e", ".")
+    session.install("asyncmock", "pytest-asyncio", "-c", constraints_path)
+
+    session.install("mock", "pytest", "pytest-cov", "-c", constraints_path)
+
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the unit tests.
     session.run(
         "py.test",
         "--quiet",
+        f"--junitxml=unit_{session.python}_sponge_log.xml",
         "--cov=google/cloud",
         "--cov=tests/unit",
         "--cov-append",
@@ -101,6 +122,9 @@ def unit(session):
 @nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)
 def system(session):
     """Run the system test suite."""
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
+    )
     system_test_path = os.path.join("tests", "system.py")
     system_test_folder_path = os.path.join("tests", "system")
 
@@ -110,6 +134,9 @@ def system(session):
     # Sanity check: Only run tests if the environment variable is set.
     if not os.environ.get("GOOGLE_APPLICATION_CREDENTIALS", ""):
         session.skip("Credentials must be set via environment variable")
+    # Install pyopenssl for mTLS testing.
+    if os.environ.get("GOOGLE_API_USE_CLIENT_CERTIFICATE", "false") == "true":
+        session.install("pyopenssl")
 
     system_test_exists = os.path.exists(system_test_path)
     system_test_folder_exists = os.path.exists(system_test_folder_path)
@@ -122,16 +149,26 @@ def system(session):
 
     # Install all test dependencies, then install this package into the
     # virtualenv's dist-packages.
-    session.install(
-        "mock", "pytest", "google-cloud-testutils",
-    )
-    session.install("-e", ".")
+    session.install("mock", "pytest", "google-cloud-testutils", "-c", constraints_path)
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the system tests.
     if system_test_exists:
-        session.run("py.test", "--quiet", system_test_path, *session.posargs)
+        session.run(
+            "py.test",
+            "--quiet",
+            f"--junitxml=system_{session.python}_sponge_log.xml",
+            system_test_path,
+            *session.posargs,
+        )
     if system_test_folder_exists:
-        session.run("py.test", "--quiet", system_test_folder_path, *session.posargs)
+        session.run(
+            "py.test",
+            "--quiet",
+            f"--junitxml=system_{session.python}_sponge_log.xml",
+            system_test_folder_path,
+            *session.posargs,
+        )
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
@@ -174,9 +211,9 @@ def docfx(session):
     """Build the docfx yaml files for this library."""
 
     session.install("-e", ".")
-    # sphinx-docfx-yaml supports up to sphinx version 1.5.5.
-    # https://github.com/docascode/sphinx-docfx-yaml/issues/97
-    session.install("sphinx==1.5.5", "alabaster", "recommonmark", "sphinx-docfx-yaml")
+    session.install(
+        "sphinx<3.0.0", "alabaster", "recommonmark", "gcp-sphinx-docfx-yaml"
+    )
 
     shutil.rmtree(os.path.join("docs", "_build"), ignore_errors=True)
     session.run(
diff --git a/renovate.json b/renovate.json
index 4fa9493..f08bc22 100644
--- a/renovate.json
+++ b/renovate.json
@@ -1,5 +1,6 @@
 {
   "extends": [
     "config:base",  ":preserveSemverRanges"
-  ]
+  ],
+  "ignorePaths": [".pre-commit-config.yaml"]
 }
diff --git a/setup.py b/setup.py
index b37923d..b1cf4db 100644
--- a/setup.py
+++ b/setup.py
@@ -28,7 +28,7 @@
 # 'Development Status :: 5 - Production/Stable'
 release_status = "Development Status :: 5 - Production/Stable"
 dependencies = [
-    "google-api-core[grpc] >= 1.22.0, < 2.0.0dev",
+    "google-api-core[grpc] >= 1.22.2, < 2.0.0dev",
     "proto-plus >= 0.4.0",
 ]
 
diff --git a/synth.metadata b/synth.metadata
index dec9fae..15307dc 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/python-iam.git",
-        "sha": "6f08bcabe0d519ffba62dba30b46a5da9bb40282"
+        "sha": "dfc7338406fc6d68e3980b240e028e0cc8097b8c"
       }
     },
     {
@@ -19,7 +19,7 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "41a4e56982620d3edcf110d76f4fcdfdec471ac8"
+        "sha": "4501974ad08b5d693311457e2ea4ce845676e329"
       }
     }
   ],
@@ -41,6 +41,7 @@
     ".github/ISSUE_TEMPLATE/feature_request.md",
     ".github/ISSUE_TEMPLATE/support_request.md",
     ".github/PULL_REQUEST_TEMPLATE.md",
+    ".github/header-checker-lint.yml",
     ".github/release-please.yml",
     ".github/snippet-bot.yml",
     ".gitignore",
@@ -65,16 +66,21 @@
     ".kokoro/samples/lint/presubmit.cfg",
     ".kokoro/samples/python3.6/common.cfg",
     ".kokoro/samples/python3.6/continuous.cfg",
+    ".kokoro/samples/python3.6/periodic-head.cfg",
     ".kokoro/samples/python3.6/periodic.cfg",
     ".kokoro/samples/python3.6/presubmit.cfg",
     ".kokoro/samples/python3.7/common.cfg",
     ".kokoro/samples/python3.7/continuous.cfg",
+    ".kokoro/samples/python3.7/periodic-head.cfg",
     ".kokoro/samples/python3.7/periodic.cfg",
     ".kokoro/samples/python3.7/presubmit.cfg",
     ".kokoro/samples/python3.8/common.cfg",
     ".kokoro/samples/python3.8/continuous.cfg",
+    ".kokoro/samples/python3.8/periodic-head.cfg",
     ".kokoro/samples/python3.8/periodic.cfg",
     ".kokoro/samples/python3.8/presubmit.cfg",
+    ".kokoro/test-samples-against-head.sh",
+    ".kokoro/test-samples-impl.sh",
     ".kokoro/test-samples.sh",
     ".kokoro/trampoline.sh",
     ".kokoro/trampoline_v2.sh",
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index ef5370f..105594f 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -5,5 +5,5 @@
 #
 # e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have foo==1.14.0
-google-api-core==1.22.0
+google-api-core==1.22.2
 proto-plus==0.4.0