chore: add jdk 8 verification to showcase CI

.github/workflows/ci.yaml

@@ -213,6 +213,62 @@ jobs:
         #  testlib modules of gax
         run: mvn package clirr:check -DskipTests -Dfmt.skip
 
+  build-java8-showcase:
+    name: "build(8) for showcase"
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-java@v4
+        with:
+          java-version: 11
+          distribution: temurin
+          cache: maven
+      - name: Install all modules using Java 11
+        shell: bash
+        run: |
+          mvn install -B -ntp -DskipTests -Dclirr.skip -Dcheckstyle.skip -Dfmt.skip
+      - uses: actions/setup-java@v3
+        with:
+          java-version: 8
+          distribution: temurin
+      - run: java -version
+      - name: Parse showcase version
+        working-directory: java-showcase/gapic-showcase
+        run: echo "SHOWCASE_VERSION=$(mvn help:evaluate -Dexpression=gapic-showcase.version -q -DforceStdout)" >> "$GITHUB_ENV"
+      - name: Install showcase server
+        run: |
+                sudo mkdir -p /usr/src/showcase
+                sudo chown -R ${USER} /usr/src/
+                curl --location https://github.com/googleapis/gapic-showcase/releases/download/v${{env.SHOWCASE_VERSION}}/gapic-showcase-${{env.SHOWCASE_VERSION}}-linux-amd64.tar.gz --output /usr/src/showcase/showcase-${{env.SHOWCASE_VERSION}}-linux-amd64.tar.gz
+                cd /usr/src/showcase/
+                tar -xf showcase-*
+                ./gapic-showcase run &
+                cd -
+      - name: Showcase integration tests
+        working-directory: java-showcase
+        run: |
+              mvn verify \
+                -P enable-integration-tests \
+                --batch-mode \
+                --no-transfer-progress
+        # The `slf4j1_logback` profile brings logging dependency and compiles logging tests, require env var to be set
+      - name: Showcase integration tests - Logging SLF4J 1.x
+        working-directory: java-showcase
+        run: |
+             mvn clean verify -P '!showcase,enable-integration-tests,loggingTestBase,slf4j1_logback' \
+              --batch-mode \
+              --no-transfer-progress
+        # Set the Env Var for this step only
+        env:
+            GOOGLE_SDK_JAVA_LOGGING: true
+        # The `disabledLogging` profile tests logging disabled when logging dependency present,
+        # do not set env var for this step
+      - name: Showcase integration tests - Logging disabed
+        working-directory: java-showcase
+        run: |
+          mvn clean verify -P '!showcase,enable-integration-tests,loggingTestBase,disabledLogging'  \
+            --batch-mode \
+            --no-transfer-progress
   showcase:
     runs-on: ubuntu-22.04
     strategy: