feat: Introduce Native Image testing build script changes (#1240)

Adds additional switch case to build.sh to accommodate native image testing.

synthtool/gcp/templates/java_library/.kokoro/build.sh

@@ -69,6 +69,11 @@ integration)
       verify
     RETURN_CODE=$?
     ;;
+graalvm)
+    # Run Unit and Integration Tests with Native Image
+    mvn test -Pnative -Penable-integration-tests
+    RETURN_CODE=$?
+    ;;
 samples)
     SAMPLES_DIR=samples
     # only run ITs in snapshot/ on presubmit PRs. run ITs in all 3 samples/ subdirectories otherwise.

synthtool/gcp/templates/java_library/.kokoro/presubmit/graalvm-native.cfg

@@ -0,0 +1,33 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Configure the docker image for kokoro-trampoline.
+env_vars: {
+  key: "TRAMPOLINE_IMAGE"
+  value: "gcr.io/cloud-devrel-kokoro-resources/graalvm"
+}
+
+env_vars: {
+  key: "JOB_TYPE"
+  value: "graalvm"
+}
+
+# TODO: remove this after we've migrated all tests and scripts
+env_vars: {
+  key: "GCLOUD_PROJECT"
+  value: "gcloud-devel"
+}
+
+env_vars: {
+  key: "GOOGLE_CLOUD_PROJECT"
+  value: "gcloud-devel"
+}
+
+env_vars: {
+  key: "GOOGLE_APPLICATION_CREDENTIALS"
+  value: "secret_manager/java-it-service-account"
+}
+
+env_vars: {
+  key: "SECRET_MANAGER_KEYS"
+  value: "java-it-service-account"
+}