diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index e3bb26e37..55bd57aa9 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -87,3 +87,27 @@ jobs:
     - run: .kokoro/build.sh
       env:
         JOB_TYPE: clirr
+  # compilation failure for sub-modules using source and target options 7 (this  setting cannot be upgraded to Java 21 because some modules support max of Java 8) 
+  # Hence compile in Java 8 and test in Java 21.    
+  units-java21:
+    # Building using Java 8 and run the tests with Java 21 runtime
+    name: "units (21)"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-java@v3
+        with:
+          java-version: 21
+          distribution: temurin
+      - name: "Set jvm system property environment variable for surefire plugin (unit tests)"
+        # Maven surefire plugin (unit tests) allows us to specify JVM to run the tests.
+        # https://maven.apache.org/surefire/maven-surefire-plugin/test-mojo.html#jvm
+        run: echo "SUREFIRE_JVM_OPT=-Djvm=${JAVA_HOME}/bin/java" >> $GITHUB_ENV
+        shell: bash
+      - uses: actions/setup-java@v3
+        with:
+          java-version: 8
+          distribution: temurin
+      - run: .kokoro/build.sh
+        env:
+          JOB_TYPE: test
diff --git a/google-http-client/src/main/java/com/google/api/client/http/HttpTransport.java b/google-http-client/src/main/java/com/google/api/client/http/HttpTransport.java
index d70d7fb5f..9a2d04220 100644
--- a/google-http-client/src/main/java/com/google/api/client/http/HttpTransport.java
+++ b/google-http-client/src/main/java/com/google/api/client/http/HttpTransport.java
@@ -21,7 +21,7 @@
 /**
  * Thread-safe abstract HTTP transport.
  *
- * <p>Implementation is thread-safe, and sub-classes must be thread-safe. For maximum efficiency,
+ * <p>Implementation is thread-safe, and subclasses must be thread-safe. For maximum efficiency,
  * applications should use a single globally-shared instance of the HTTP transport.
  *
  * <p>The recommended concrete implementation HTTP transport library to use depends on what
@@ -158,4 +158,14 @@ public boolean isMtls() {
    * @since 1.4
    */
   public void shutdown() throws IOException {}
+
+  /**
+   * Returns whether the transport is shutdown or not.
+   *
+   * @return true if the transport is shutdown.
+   * @since 1.44.0
+   */
+  public boolean isShutdown() {
+    return true;
+  }
 }
diff --git a/owlbot.py b/owlbot.py
index 44a59dd69..6c8dbbb8a 100644
--- a/owlbot.py
+++ b/owlbot.py
@@ -29,6 +29,7 @@
         "license-checks.xml",
         ".github/workflows/samples.yaml",
         ".kokoro/build.sh",
-        "renovate.json"
+        "renovate.json",
+        ".github/workflows/ci.yaml"
     ]
 )