improve: dependent resource can be re-initialized

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/source/informer/InformerEventSource.java

@@ -365,7 +365,7 @@ public void setConfigurationService(ConfigurationService configurationService) {
     super.setConfigurationService(configurationService);
 
     cache.addIndexers(indexerBuffer);
-    indexerBuffer = null;
+    indexerBuffer = new HashMap<>(0);
   }
 
   public void addIndexers(Map<String, Function<R, List<String>>> indexers) {

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

@@ -0,0 +1,39 @@
+package io.javaoperatorsdk.operator;
+
+import org.junit.jupiter.api.Test;
+
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.fabric8.kubernetes.client.KubernetesClientBuilder;
+import io.javaoperatorsdk.operator.junit.LocallyRunOperatorExtension;
+import io.javaoperatorsdk.operator.sample.dependentreinitialization.ConfigMapDependentResource;
+import io.javaoperatorsdk.operator.sample.dependentreinitialization.DependentReInitializationCustomResource;
+import io.javaoperatorsdk.operator.sample.dependentreinitialization.DependentReInitializationReconciler;
+
+class DependentReInitializationIT {
+
+  /**
+   * In case dependent resource is managed by CDI (like in Quarkus) can be handy that the instance
+   * is reused in tests.
+   */
+  @Test
+  void dependentCanDeReInitialized() {
+    var client = new KubernetesClientBuilder().build();
+    LocallyRunOperatorExtension.applyCrd(DependentReInitializationCustomResource.class, client);
+
+    var dependent = new ConfigMapDependentResource();
+
+    startEndStopOperator(client, dependent);
+    startEndStopOperator(client, dependent);
+  }
+
+  private static void startEndStopOperator(KubernetesClient client,
+      ConfigMapDependentResource dependent) {
+    Operator o1 = new Operator(o -> o
+        .withCloseClientOnStop(false)
+        .withKubernetesClient(client));
+    o1.register(new DependentReInitializationReconciler(dependent, client));
+    o1.start();
+    o1.stop();
+  }
+
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/dependentreinitialization/ConfigMapDependentResource.java

@@ -0,0 +1,29 @@
+package io.javaoperatorsdk.operator.sample.dependentreinitialization;
+
+import java.util.Map;
+
+import io.fabric8.kubernetes.api.model.ConfigMap;
+import io.fabric8.kubernetes.api.model.ConfigMapBuilder;
+import io.fabric8.kubernetes.api.model.ObjectMetaBuilder;
+import io.javaoperatorsdk.operator.api.reconciler.Context;
+import io.javaoperatorsdk.operator.processing.dependent.kubernetes.CRUDKubernetesDependentResource;
+
+public class ConfigMapDependentResource
+    extends CRUDKubernetesDependentResource<ConfigMap, DependentReInitializationCustomResource> {
+
+  public ConfigMapDependentResource() {
+    super(ConfigMap.class);
+  }
+
+  @Override
+  protected ConfigMap desired(DependentReInitializationCustomResource primary,
+      Context<DependentReInitializationCustomResource> context) {
+    return new ConfigMapBuilder()
+        .withMetadata(new ObjectMetaBuilder()
+            .withName(primary.getMetadata().getName())
+            .withNamespace(primary.getMetadata().getNamespace())
+            .build())
+        .withData(Map.of("key", "val"))
+        .build();
+  }
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/dependentreinitialization/DependentReInitializationCustomResource.java

@@ -0,0 +1,14 @@
+package io.javaoperatorsdk.operator.sample.dependentreinitialization;
+
+import io.fabric8.kubernetes.api.model.Namespaced;
+import io.fabric8.kubernetes.client.CustomResource;
+import io.fabric8.kubernetes.model.annotation.Group;
+import io.fabric8.kubernetes.model.annotation.Version;
+
+@Group("sample.javaoperatorsdk")
+@Version("v1")
+public class DependentReInitializationCustomResource
+    extends CustomResource<Void, Void>
+    implements Namespaced {
+
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/dependentreinitialization/DependentReInitializationReconciler.java

@@ -0,0 +1,38 @@
+package io.javaoperatorsdk.operator.sample.dependentreinitialization;
+
+import java.util.Map;
+
+import io.fabric8.kubernetes.client.KubernetesClient;
+import io.javaoperatorsdk.operator.api.reconciler.*;
+import io.javaoperatorsdk.operator.processing.event.source.EventSource;
+
+@ControllerConfiguration
+public class DependentReInitializationReconciler
+    implements Reconciler<DependentReInitializationCustomResource>,
+    EventSourceInitializer<DependentReInitializationCustomResource> {
+
+  private final ConfigMapDependentResource configMapDependentResource;
+
+  public DependentReInitializationReconciler(ConfigMapDependentResource dependentResource,
+      KubernetesClient client) {
+    this.configMapDependentResource = dependentResource;
+    this.configMapDependentResource.setKubernetesClient(client);
+  }
+
+  @Override
+  public UpdateControl<DependentReInitializationCustomResource> reconcile(
+      DependentReInitializationCustomResource resource,
+      Context<DependentReInitializationCustomResource> context) throws Exception {
+    configMapDependentResource.reconcile(resource, context);
+    return UpdateControl.noUpdate();
+  }
+
+  @Override
+  public Map<String, EventSource> prepareEventSources(
+      EventSourceContext<DependentReInitializationCustomResource> context) {
+    return EventSourceInitializer.nameEventSourcesFromDependentResource(context,
+        configMapDependentResource);
+  }
+
+
+}