ci: release=8 for JDK 9+ (#478)

* ci: release=8 for JDK 9+

* ci: removing "dependencies (8)"

.github/sync-repo-settings.yaml

@@ -29,7 +29,6 @@ branchProtectionRules:
   requiresStrictStatusChecks: false
   # List of required status check contexts that must pass for commits to be accepted to matching branches.
   requiredStatusCheckContexts:
-    - "dependencies (8)"
     - "dependencies (11)"
     - "lint"
     - "clirr"

.github/workflows/downstream-dependencies.yaml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java: [8, 11]
+        java: [11]
         repo:
         - java-bigquery
         - java-bigqueryconnection
@@ -27,5 +27,3 @@ jobs:
     - run: sudo apt-get update -y
     - run: sudo apt-get install libxml2-utils
     - run: .kokoro/client-library-check.sh ${{matrix.repo}} dependencies
-      if: ${{matrix.java != '8' }}
-      # Always successful for Java 8, which we'll remove soon

pom.xml

@@ -833,6 +833,17 @@
         </plugins>
       </build>
     </profile>
-
+    <profile>
+      <!-- JDK 9+ has the "release" option to ensure the generated bytecode is
+        compatible with Java 8. Maven-compiler-plugin's "<target>1.8</target>" is
+        not sufficient. -->
+      <id>compiler-release-8</id>
+      <activation>
+        <jdk>[9,]</jdk>
+      </activation>
+      <properties>
+        <maven.compiler.release>8</maven.compiler.release>
+      </properties>
+    </profile>
   </profiles>
 </project>