@@ -28,11 +28,23 @@ function update_config() {
     sed -i -e "s/^${key_word}.*$/${key_word}: ${new_value}/" "${file}"
 }
 
+# Update an action to a new version in GitHub action.
+function update_action() {
+    local key_word=$1
+    local new_value=$2
+    local file=$3
+    echo "Update ${key_word} to ${new_value} in ${file}"
+    # use a different delimiter because the key_word contains "/".
+    sed -i -e "s|${key_word}@v.*$|${key_word}@v${new_value}|" "${file}"
+}
+
 # The parameters of this script is:
 # 1. base_branch, the base branch of the result pull request.
 # 2. repo, organization/repo-name, e.g., googleapis/google-cloud-java
 # 3. [optional] generation_config, the path to the generation configuration,
 # the default value is generation_config.yaml in the repository root.
+# 4. [optional] workflow, the library generation workflow file,
+# the default value is .github/workflows/hermetic_library_generation.yaml.
 while [[ $# -gt 0 ]]; do
 key="$1"
 case "${key}" in
@@ -48,6 +60,10 @@ case "${key}" in
     generation_config="$2"
     shift
     ;;
+  --workflow)
+    workflow="$2"
+    shift
+    ;;
   *)
     echo "Invalid option: [$1]"
     exit 1
@@ -71,21 +87,34 @@ if [ -z "${generation_config}" ]; then
   echo "Use default generation config: ${generation_config}"
 fi
 
+if [ -z "${workflow}" ]; then
+    workflow=".github/workflows/hermetic_library_generation.yaml"
+    echo "Use default library generation workflow file: ${workflow}"
+fi
+
 current_branch="generate-libraries-${base_branch}"
 title="chore: Update generation configuration at $(date)"
 
-# try to find a open pull request associated with the branch
+git checkout "${base_branch}"
+# Try to find a open pull request associated with the branch
 pr_num=$(gh pr list -s open -H "${current_branch}" -q . --json number | jq ".[] | .number")
-# create a branch if there's no open pull request associated with the
+# Create a branch if there's no open pull request associated with the
 # branch; otherwise checkout the pull request.
 if [ -z "${pr_num}" ]; then
   git checkout -b "${current_branch}"
+  # Push the current branch to remote so that we can
+  # compare the commits later.
+  git push -u origin "${current_branch}"
 else
   gh pr checkout "${pr_num}"
 fi
 
+# Only allow fast-forward merging; exit with non-zero result if there's merging
+# conflict.
+git merge -m "chore: merge ${base_branch} into ${current_branch}" "${base_branch}"
+
 mkdir tmp-googleapis
-# use partial clone because only commit history is needed.
+# Use partial clone because only commit history is needed.
 git clone --filter=blob:none https://github.com/googleapis/googleapis.git tmp-googleapis
 pushd tmp-googleapis
 git pull
@@ -94,25 +123,43 @@ popd
 rm -rf tmp-googleapis
 update_config "googleapis_commitish" "${latest_commit}" "${generation_config}"
 
-# update gapic-generator-java version to the latest
+# Update gapic-generator-java version to the latest
 latest_version=$(get_latest_released_version "com.google.api" "gapic-generator-java")
 update_config "gapic_generator_version" "${latest_version}" "${generation_config}"
 
-# update libraries-bom version to the latest
+# Update composite action version to latest gapic-generator-java version
+update_action "googleapis/sdk-platform-java/.github/scripts" \
+  "${latest_version}" \
+  "${workflow}"
+
+# Update libraries-bom version to the latest
 latest_version=$(get_latest_released_version "com.google.cloud" "libraries-bom")
 update_config "libraries_bom_version" "${latest_version}" "${generation_config}"
 
-git add "${generation_config}"
+git add "${generation_config}" "${workflow}"
 changed_files=$(git diff --cached --name-only)
 if [[ "${changed_files}" == "" ]]; then
     echo "The latest generation config is not changed."
     echo "Skip committing to the pull request."
+else
+    git commit -m "${title}"
+fi
+
+# There are potentially at most two commits: merge commit and change commit.
+# We want to exit the script if no commit happens (otherwise this will be an
+# infinite loop).
+# `git cherry` is a way to find whether the local branch has commits that are
+# not in the remote branch.
+# If we find any such commit, push them to remote branch.
+unpushed_commit=$(git cherry -v "origin/${current_branch}" | wc -l)
+if [[ "${unpushed_commit}" -eq 0 ]]; then
+    echo "No unpushed commits, exit"
     exit 0
 fi
-git commit -m "${title}"
+
 if [ -z "${pr_num}" ]; then
   git remote add remote_repo https://cloud-java-bot:"${GH_TOKEN}@github.com/${repo}.git"
-  git fetch -q --unshallow remote_repo
+  git fetch -q remote_repo
   git push -f remote_repo "${current_branch}"
   gh pr create --title "${title}" --head "${current_branch}" --body "${title}" --base "${base_branch}"
 else
 
@@ -49,7 +49,7 @@ If you are using Maven without the BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies:
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:26.50.0')
+implementation platform('com.google.cloud:libraries-bom:26.51.0')
 
 implementation 'com.google.cloud:google-cloud-spanner'
 ```
 
@@ -1,6 +1,6 @@
-gapic_generator_version: 2.50.0
-googleapis_commitish: 349841abac6c3e580ccce6e3d6fcc182ed2512c2
-libraries_bom_version: 26.50.0
+gapic_generator_version: 2.51.0
+googleapis_commitish: 7d0c6bee2517d77635beb2a1dd6d6e7d4d943512
+libraries_bom_version: 26.51.0
 libraries:
   - api_shortname: spanner
     name_pretty: Cloud Spanner
 
@@ -228,6 +228,17 @@ public enum TypeCode implements com.google.protobuf.ProtocolMessageEnum {
    * <code>INTERVAL = 16;</code>
    */
   INTERVAL(16),
+  /**
+   *
+   *
+   * <pre>
+   * Encoded as `string`, in lower-case hexa-decimal format, as described
+   * in RFC 9562, section 4.
+   * </pre>
+   *
+   * <code>UUID = 17;</code>
+   */
+  UUID(17),
   UNRECOGNIZED(-1),
   ;
 
@@ -424,6 +435,17 @@ public enum TypeCode implements com.google.protobuf.ProtocolMessageEnum {
    * <code>INTERVAL = 16;</code>
    */
   public static final int INTERVAL_VALUE = 16;
+  /**
+   *
+   *
+   * <pre>
+   * Encoded as `string`, in lower-case hexa-decimal format, as described
+   * in RFC 9562, section 4.
+   * </pre>
+   *
+   * <code>UUID = 17;</code>
+   */
+  public static final int UUID_VALUE = 17;
 
   public final int getNumber() {
     if (this == UNRECOGNIZED) {
@@ -481,6 +503,8 @@ public static TypeCode forNumber(int value) {
         return ENUM;
       case 16:
         return INTERVAL;
+      case 17:
+        return UUID;
       default:
         return null;
     }
 
@@ -60,20 +60,20 @@ public static com.google.protobuf.Descriptors.FileDescriptor getDescriptor() {
           + "pe_fqn\030\005 \001(\t\"\177\n\nStructType\0223\n\006fields\030\001 \003"
           + "(\0132#.google.spanner.v1.StructType.Field\032"
           + "<\n\005Field\022\014\n\004name\030\001 \001(\t\022%\n\004type\030\002 \001(\0132\027.g"
-          + "oogle.spanner.v1.Type*\325\001\n\010TypeCode\022\031\n\025TY"
+          + "oogle.spanner.v1.Type*\337\001\n\010TypeCode\022\031\n\025TY"
           + "PE_CODE_UNSPECIFIED\020\000\022\010\n\004BOOL\020\001\022\t\n\005INT64"
           + "\020\002\022\013\n\007FLOAT64\020\003\022\013\n\007FLOAT32\020\017\022\r\n\tTIMESTAM"
           + "P\020\004\022\010\n\004DATE\020\005\022\n\n\006STRING\020\006\022\t\n\005BYTES\020\007\022\t\n\005"
           + "ARRAY\020\010\022\n\n\006STRUCT\020\t\022\013\n\007NUMERIC\020\n\022\010\n\004JSON"
-          + "\020\013\022\t\n\005PROTO\020\r\022\010\n\004ENUM\020\016\022\014\n\010INTERVAL\020\020*d\n"
-          + "\022TypeAnnotationCode\022$\n TYPE_ANNOTATION_C"
-          + "ODE_UNSPECIFIED\020\000\022\016\n\nPG_NUMERIC\020\002\022\014\n\010PG_"
-          + "JSONB\020\003\022\n\n\006PG_OID\020\004B\254\001\n\025com.google.spann"
-          + "er.v1B\tTypeProtoP\001Z5cloud.google.com/go/"
-          + "spanner/apiv1/spannerpb;spannerpb\252\002\027Goog"
-          + "le.Cloud.Spanner.V1\312\002\027Google\\Cloud\\Spann"
-          + "er\\V1\352\002\032Google::Cloud::Spanner::V1b\006prot"
-          + "o3"
+          + "\020\013\022\t\n\005PROTO\020\r\022\010\n\004ENUM\020\016\022\014\n\010INTERVAL\020\020\022\010\n"
+          + "\004UUID\020\021*d\n\022TypeAnnotationCode\022$\n TYPE_AN"
+          + "NOTATION_CODE_UNSPECIFIED\020\000\022\016\n\nPG_NUMERI"
+          + "C\020\002\022\014\n\010PG_JSONB\020\003\022\n\n\006PG_OID\020\004B\254\001\n\025com.go"
+          + "ogle.spanner.v1B\tTypeProtoP\001Z5cloud.goog"
+          + "le.com/go/spanner/apiv1/spannerpb;spanne"
+          + "rpb\252\002\027Google.Cloud.Spanner.V1\312\002\027Google\\C"
+          + "loud\\Spanner\\V1\352\002\032Google::Cloud::Spanner"
+          + "::V1b\006proto3"
     };
     descriptor =
         com.google.protobuf.Descriptors.FileDescriptor.internalBuildGeneratedFileFrom(
 
@@ -175,6 +175,10 @@ enum TypeCode {
   // For example, `P1Y2M3DT4H5M6.5S` represents time duration of 1 year, 2
   // months, 3 days, 4 hours, 5 minutes, and 6.5 seconds.
   INTERVAL = 16;
+
+  // Encoded as `string`, in lower-case hexa-decimal format, as described
+  // in RFC 9562, section 4.
+  UUID = 17;
 }
 
 // `TypeAnnotationCode` is used as a part of [Type][google.spanner.v1.Type] to
 
@@ -41,16 +41,6 @@
       ],
       "depNameTemplate": "com.google.cloud:sdk-platform-java-config",
       "datasourceTemplate": "maven"
-    },
-    {
-      "fileMatch": [
-        "^.github/workflows/hermetic_library_generation.yaml$"
-      ],
-      "matchStrings": [
-        "uses: googleapis/sdk-platform-java/.github/scripts@v(?<currentValue>.+?)\\n"
-      ],
-      "depNameTemplate": "com.google.api:gapic-generator-java",
-      "datasourceTemplate": "maven"
     }
   ],
   "packageRules": [
@@ -111,13 +101,6 @@
         "^com.fasterxml.jackson.core"
       ],
       "groupName": "jackson dependencies"
-    },
-    {
-      "matchPackagePatterns": [
-        "^com.google.api:gapic-generator-java",
-        "^com.google.cloud:sdk-platform-java-config"
-      ],
-      "groupName": "SDK platform Java dependencies"
     }
   ],
   "semanticCommits": true,