chore: improve monorepo migration tooling

.github/workflows/ci.yaml

@@ -112,6 +112,7 @@ jobs:
     outputs:
       packages: ${{ steps.filter.outputs.changes }}
     steps:
+    - uses: actions/checkout@v4
     - uses: dorny/paths-filter@fbd0ab8f3e69293af611ebaee6363fc25e6d187d # v4.0.1
       id: filter
       with:
@@ -338,8 +339,8 @@ jobs:
     - run: .kokoro/build.sh
       env:
         JOB_TYPE: lint
-        HEAD_SHA: ${{ github.event.pull_request.head.sha }}
-        BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        HEAD_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
+        BASE_SHA: ${{ github.event.pull_request.base.sha || github.event.before }}
   enforcer:
     runs-on: ubuntu-latest
     steps:

.github/workflows/java-bigtable-ci.yaml

@@ -137,8 +137,8 @@ jobs:
     - run: .kokoro/build.sh
       env:
         JOB_TYPE: lint
-        HEAD_SHA: ${{ github.event.pull_request.head.sha }}
-        BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        HEAD_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
+        BASE_SHA: ${{ github.event.pull_request.base.sha || github.event.before }}
   clirr:
     needs: filter
     if: ${{ needs.filter.outputs.library == 'true' }}

.github/workflows/java-pubsub-ci.yaml

@@ -137,8 +137,8 @@ jobs:
     - run: .kokoro/build.sh
       env:
         JOB_TYPE: lint
-        HEAD_SHA: ${{ github.event.pull_request.head.sha }}
-        BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        HEAD_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
+        BASE_SHA: ${{ github.event.pull_request.base.sha || github.event.before }}
   clirr:
     needs: filter
     if: ${{ needs.filter.outputs.library == 'true' }}

.github/workflows/java-spanner-jdbc-ci.yaml

@@ -141,8 +141,8 @@ jobs:
     - run: .kokoro/build.sh
       env:
         JOB_TYPE: lint
-        HEAD_SHA: ${{ github.event.pull_request.head.sha }}
-        BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        HEAD_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
+        BASE_SHA: ${{ github.event.pull_request.base.sha || github.event.before }}
   required:
     needs: [ units, units-java8, windows, dependencies, javadoc, lint ]
     name: conditional-required-check

.github/workflows/java-storage-nio-ci.yaml

@@ -141,8 +141,8 @@ jobs:
     - run: .kokoro/build.sh
       env:
         JOB_TYPE: lint
-        HEAD_SHA: ${{ github.event.pull_request.head.sha }}
-        BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        HEAD_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
+        BASE_SHA: ${{ github.event.pull_request.base.sha || github.event.before }}
   required:
     needs: [ units, units-java8, windows, dependencies, javadoc, lint ]
     name: conditional-required-check

generation/apply_versions.sh

@@ -25,7 +25,7 @@ if [[ "$column_name" == "released" ]]; then
   column_index=2
 elif [[ "$column_name" == "current" ]]; then
   column_index=3
-elif "$column_name" != "current" ]]; then
+elif [[ "$column_name" != "current" ]]; then
   echo "Error: column_name must be either 'released' or 'current'"
   exit 1
 fi

generation/update_owlbot_postprocessor_config.sh

@@ -6,7 +6,10 @@
 
 set -e
 
-for dir in $(find . -mindepth 2 -maxdepth 2 -name owlbot.py | grep -v 'java-common-protos/' | grep -v 'java-iam/' | grep -v 'java-showcase/' | sort | xargs dirname ); do
+TARGET_MODULE="${1:-.}"
+
+for owlbot_script in $(find "$TARGET_MODULE" -name owlbot.py | grep -v 'java-common-protos/' | grep -v 'java-iam/' | grep -v 'java-showcase/' | sort); do
+  dir=$(dirname "$owlbot_script")
   pushd "$dir"
 
   # form a perl command to replace java.common_templates() invocation

monorepo-migration/.gitignore

@@ -0,0 +1,3 @@
+.git-filter-repo/
+__pycache__/
+*.pyc

monorepo-migration/migrate-bigtable.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+# Copyright 2026 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.
+
+# Exit on error
+set -e
+
+# Get absolute paths
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+MONOREPO_ROOT="$(dirname "$SCRIPT_DIR")"
+
+echo "========================================================"
+echo " Staging java-bigtable migration"
+echo "========================================================"
+
+# 1. Configure environment for the base migrate.sh script
+export SOURCE_REPO_URL="https://github.com/googleapis/java-bigtable"
+export MIGRATION_HEAD_BRANCH="main"
+export SQUASH_COMMITS="false"
+export CODEOWNER="@googleapis/bigtable-team" 
+export BOM_SUBSTITUTIONS="gapic-libraries-bom:google-cloud-monitoring-bom" 
+export PRE_INSTALL_DEPS="java-monitoring/google-cloud-monitoring-bom,java-monitoring/google-cloud-monitoring" 
+
+# 2. Execute the central migration script
+"${SCRIPT_DIR}/migrate.sh"
+
+echo ""
+echo "========================================================"
+echo "Migration staged successfully!"
+echo "Results are available in the isolated clone:"
+echo "  migration-work/google-cloud-java-target"
+echo "Current Branch: migrate-java-bigtable"
+echo "Next Steps: cd migration-work/google-cloud-java-target && mvn clean install -DskipTests"
+echo "========================================================"

monorepo-migration/migrate-firestore.sh

@@ -0,0 +1,43 @@
+#!/bin/bash
+# Copyright 2026 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.
+
+# Exit on error
+set -e
+
+# Get absolute paths
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+MONOREPO_ROOT="$(dirname "$SCRIPT_DIR")"
+
+echo "========================================================"
+echo " Staging java-firestore migration"
+echo "========================================================"
+
+# 1. Configure environment for the base migrate.sh script
+export SOURCE_REPO_URL="https://github.com/googleapis/java-firestore"
+export MIGRATION_HEAD_BRANCH="main"
+export SQUASH_COMMITS="false"
+export CODEOWNER="@googleapis/firestore-team" 
+
+# 2. Execute the central migration script
+"${SCRIPT_DIR}/migrate.sh"
+
+echo ""
+echo "========================================================"
+echo "Migration staged successfully!"
+echo "Results are available in the isolated clone:"
+echo "  migration-work/google-cloud-java-target"
+echo "Current Branch: migrate-java-firestore"
+echo "Next Steps: cd migration-work/google-cloud-java-target && mvn clean install -DskipTests"
+echo "========================================================"

monorepo-migration/migrate-pubsub.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+# Copyright 2026 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.
+
+# Exit on error
+set -e
+
+# Get absolute paths
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+MONOREPO_ROOT="$(dirname "$SCRIPT_DIR")"
+
+echo "========================================================"
+echo " Staging java-pubsub migration"
+echo "========================================================"
+
+# 1. Configure environment for the base migrate.sh script
+export SOURCE_REPO_URL="https://github.com/googleapis/java-pubsub"
+export MIGRATION_HEAD_BRANCH="main"
+export SQUASH_COMMITS="false"
+export CODEOWNER="@googleapis/pubsub-team" 
+export SUREFIRE_JVM_OPT="-DskipTests"
+
+# 2. Execute the central migration script
+# This performs git read-tree, POM modernization, workflow transformation, and generation config updates.
+# Note: migrate.sh works in an isolated sibling clone to avoid polluting the active workspace.
+"${SCRIPT_DIR}/migrate.sh"
+
+echo ""
+echo "========================================================"
+echo "Migration staged successfully!"
+echo "Results are available in the isolated clone:"
+echo "  ../../migration-work/google-cloud-java-target"
+echo "Current Branch: migrate-java-pubsub"
+echo "Next Steps: cd ../../migration-work/google-cloud-java-target && mvn clean install -DskipTests"
+echo "========================================================"