Fix checkstyle, fix tests

Author: Abacn

sdks/java/testing/junit/build.gradle

@@ -32,6 +32,7 @@ dependencies {
   // Needed to resolve TestPipeline's JUnit 4 TestRule type and @Category at compile time,
   // but should not leak to consumers at runtime.
   provided library.java.junit
+  permitUnusedDeclared(library.java.junit)
 
   // JUnit 5 API needed to compile the extension; not packaged for consumers of core.
   provided library.java.jupiter_api

sdks/java/testing/junit/src/main/java/org/apache/beam/sdk/testing/TestPipelineExtension.java

@@ -24,7 +24,7 @@
 import java.util.Collection;
 import org.apache.beam.sdk.options.ApplicationNameOptions;
 import org.apache.beam.sdk.options.PipelineOptions;
-import org.apache.beam.vendor.grpc.v1p69p0.com.google.common.collect.ImmutableList;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.junit.jupiter.api.extension.AfterEachCallback;
 import org.junit.jupiter.api.extension.BeforeEachCallback;

sdks/java/testing/junit/src/test/java/org/apache/beam/sdk/testing/TestPipelineExtensionAdvancedTest.java

@@ -20,6 +20,7 @@
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.io.Serializable;
 import org.apache.beam.sdk.options.ApplicationNameOptions;
 import org.apache.beam.sdk.transforms.Create;
 import org.apache.beam.sdk.transforms.DoFn;
@@ -31,7 +32,7 @@
 
 /** Advanced tests for {@link TestPipelineExtension} demonstrating comprehensive functionality. */
 @ExtendWith(TestPipelineExtension.class)
-public class TestPipelineExtensionAdvancedTest {
+public class TestPipelineExtensionAdvancedTest implements Serializable {
 
   @Test
   public void testApplicationNameIsSet(TestPipeline pipeline) {
@@ -72,7 +73,7 @@ public void testWithValidatesRunnerCategory(TestPipeline pipeline) {
   @Test
   public void testPipelineInstancesAreIsolated(TestPipeline pipeline1) {
     // Each test method gets its own pipeline instance
-    assertNotNull(pipeline1);
+    pipeline1.enableAutoRunIfMissing(true);
     pipeline1.apply("Create", Create.of("test"));
     // Don't run the pipeline - test should still pass due to auto-run functionality
   }