fix: cleaner issue for pod caused by missing generation in metadata

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/source/controller/InternalEventFilters.java

@@ -18,6 +18,11 @@ static <T extends HasMetadata> OnUpdateFilter<T> onUpdateGenerationAware(
       if (!generationAware) {
         return true;
       }
+      // for example pods don't have generation
+      if (oldResource.getMetadata().getGeneration() == null) {
+        return true;
+      }
+
       return oldResource.getMetadata().getGeneration() < newResource
           .getMetadata().getGeneration();
     };

operator-framework/src/test/java/io/javaoperatorsdk/operator/BuiltInResourceCleanerIT.java

@@ -0,0 +1,55 @@
+package io.javaoperatorsdk.operator;
+
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.fabric8.kubernetes.api.model.Pod;
+import io.javaoperatorsdk.operator.junit.LocallyRunOperatorExtension;
+import io.javaoperatorsdk.operator.sample.builtinresourcecleaner.ObservedGenerationTestReconciler;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.awaitility.Awaitility.await;
+
+class BuiltInResourceCleanerIT {
+
+  private static final Logger log = LoggerFactory.getLogger(BuiltInResourceCleanerIT.class);
+
+  @RegisterExtension
+  LocallyRunOperatorExtension operator =
+      LocallyRunOperatorExtension.builder()
+          .withReconciler(new ObservedGenerationTestReconciler())
+          .build();
+
+  @Test
+  void cleanerIsCalledOnBuiltInResource() {
+    var pod = operator.create(testPod());
+
+    await().untilAsserted(() -> {
+      assertThat(operator.getReconcilerOfType(ObservedGenerationTestReconciler.class)
+          .getReconcileCount()).isPositive();
+      var actualPod = operator.get(Pod.class, pod.getMetadata().getName());
+      assertThat(actualPod.getMetadata().getFinalizers()).isNotEmpty();
+    });
+
+    log.info("Deleting pod");
+    operator.delete(pod);
+
+    await().untilAsserted(() -> {
+      assertThat(operator.getReconcilerOfType(ObservedGenerationTestReconciler.class)
+          .getCleanCount()).isPositive();
+    });
+    log.info("everything ok, actual pod: {}", operator.get(Pod.class, pod.getMetadata().getName()));
+  }
+
+  Pod testPod() {
+    Pod pod = ReconcilerUtils.loadYaml(Pod.class, StandaloneDependentResourceIT.class,
+        "pod-template.yaml");
+    pod.getMetadata().setLabels(Map.of("builtintest", "true"));
+    return pod;
+  }
+
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/builtinresourcecleaner/ObservedGenerationTestReconciler.java

@@ -0,0 +1,41 @@
+package io.javaoperatorsdk.operator.sample.builtinresourcecleaner;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.fabric8.kubernetes.api.model.Pod;
+import io.javaoperatorsdk.operator.api.reconciler.*;
+
+@ControllerConfiguration(labelSelector = "builtintest=true")
+public class ObservedGenerationTestReconciler
+    implements Reconciler<Pod>, Cleaner<Pod> {
+
+  private static final Logger log = LoggerFactory.getLogger(ObservedGenerationTestReconciler.class);
+
+  private AtomicInteger reconciled = new AtomicInteger(0);
+  private AtomicInteger cleaned = new AtomicInteger(0);
+
+  @Override
+  public UpdateControl<Pod> reconcile(
+      Pod resource,
+      Context<Pod> context) {
+    reconciled.addAndGet(1);
+    return UpdateControl.noUpdate();
+  }
+
+  @Override
+  public DeleteControl cleanup(Pod resource, Context<Pod> context) {
+    cleaned.addAndGet(1);
+    return DeleteControl.defaultDelete();
+  }
+
+  public int getReconcileCount() {
+    return reconciled.get();
+  }
+
+  public int getCleanCount() {
+    return cleaned.get();
+  }
+}

operator-framework/src/test/resources/io/javaoperatorsdk/operator/pod-template.yaml

@@ -0,0 +1,10 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: test-pod
+spec:
+  containers:
+    - name: nginx
+      image: nginx:1.14.2
+      ports:
+        - containerPort: 80