feat: showcase sample for matcher with ssa in DR

docs/documentation/v4-4-migration.md

@@ -77,7 +77,7 @@ the `KubernetesDependentResource`.
 
 The SSA based create/update can be combined with the legacy matcher, simply override the `match` method 
 and use the [GenericKubernetesResourceMatcher](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/dependent/kubernetes/GenericKubernetesResourceMatcher.java#L19-L19)
-directly.
+directly. See related [sample](https://github.com/java-operator-sdk/java-operator-sdk/blob/main/operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/ssalegacymatcher/ServiceDependentResource.java#L39-L44).
 
 ### Migration from plain Update/Create to SSA Based Patch
 

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/dependent/kubernetes/GenericKubernetesResourceMatcher.java

@@ -19,7 +19,7 @@
 public class GenericKubernetesResourceMatcher<R extends HasMetadata, P extends HasMetadata>
     implements Matcher<R, P> {
 
-  private static String SPEC = "/spec";
+  private static final String SPEC = "/spec";
   private static final String ADD = "add";
   private static final String OP = "op";
   public static final String METADATA_LABELS = "/metadata/labels";

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

@@ -0,0 +1,53 @@
+package io.javaoperatorsdk.operator;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.fabric8.kubernetes.api.model.ObjectMetaBuilder;
+import io.fabric8.kubernetes.api.model.Service;
+import io.javaoperatorsdk.operator.junit.LocallyRunOperatorExtension;
+import io.javaoperatorsdk.operator.sample.ssalegacymatcher.SSALegacyMatcherCustomResource;
+import io.javaoperatorsdk.operator.sample.ssalegacymatcher.SSALegacyMatcherReconciler;
+import io.javaoperatorsdk.operator.sample.ssalegacymatcher.SSALegacyMatcherSpec;
+import io.javaoperatorsdk.operator.sample.ssalegacymatcher.ServiceDependentResource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.awaitility.Awaitility.await;
+
+public class SSAWithLegacyMatcherIT {
+
+  public static final String TEST_RESOURCE_NAME = "test1";
+
+  @RegisterExtension
+  LocallyRunOperatorExtension extension =
+      LocallyRunOperatorExtension.builder().withReconciler(new SSALegacyMatcherReconciler())
+          .build();
+
+  @Test
+  void matchesDependentWithLegacyMatcher() {
+    var resource = extension.create(testResource());
+
+    await().untilAsserted(() -> {
+      var service = extension.get(Service.class, TEST_RESOURCE_NAME);
+      assertThat(service).isNotNull();
+      assertThat(ServiceDependentResource.createUpdateCount.get()).isEqualTo(1);
+    });
+
+    resource.getSpec().setValue("other_value");
+
+    await().untilAsserted(() -> {
+      assertThat(ServiceDependentResource.createUpdateCount.get()).isEqualTo(1);
+    });
+  }
+
+  SSALegacyMatcherCustomResource testResource() {
+    SSALegacyMatcherCustomResource res = new SSALegacyMatcherCustomResource();
+    res.setMetadata(new ObjectMetaBuilder()
+        .withName(TEST_RESOURCE_NAME)
+        .build());
+    res.setSpec(new SSALegacyMatcherSpec());
+    res.getSpec().setValue("initial-value");
+    return res;
+  }
+
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/ssalegacymatcher/SSALegacyMatcherCustomResource.java

@@ -0,0 +1,16 @@
+package io.javaoperatorsdk.operator.sample.ssalegacymatcher;
+
+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.ShortNames;
+import io.fabric8.kubernetes.model.annotation.Version;
+
+@Group("sample.javaoperatorsdk")
+@Version("v1")
+@ShortNames("slm")
+public class SSALegacyMatcherCustomResource
+    extends CustomResource<SSALegacyMatcherSpec, Void>
+    implements Namespaced {
+
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/ssalegacymatcher/SSALegacyMatcherReconciler.java

@@ -0,0 +1,28 @@
+package io.javaoperatorsdk.operator.sample.ssalegacymatcher;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import io.javaoperatorsdk.operator.api.reconciler.Context;
+import io.javaoperatorsdk.operator.api.reconciler.ControllerConfiguration;
+import io.javaoperatorsdk.operator.api.reconciler.Reconciler;
+import io.javaoperatorsdk.operator.api.reconciler.UpdateControl;
+import io.javaoperatorsdk.operator.api.reconciler.dependent.Dependent;
+
+@ControllerConfiguration(dependents = {@Dependent(type = ServiceDependentResource.class)})
+public class SSALegacyMatcherReconciler
+    implements Reconciler<SSALegacyMatcherCustomResource> {
+
+  private final AtomicInteger numberOfExecutions = new AtomicInteger(0);
+
+  @Override
+  public UpdateControl<SSALegacyMatcherCustomResource> reconcile(
+      SSALegacyMatcherCustomResource resource,
+      Context<SSALegacyMatcherCustomResource> context) {
+    numberOfExecutions.addAndGet(1);
+    return UpdateControl.noUpdate();
+  }
+
+  public int getNumberOfExecutions() {
+    return numberOfExecutions.get();
+  }
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/ssalegacymatcher/SSALegacyMatcherSpec.java

@@ -0,0 +1,15 @@
+package io.javaoperatorsdk.operator.sample.ssalegacymatcher;
+
+public class SSALegacyMatcherSpec {
+
+  private String value;
+
+  public String getValue() {
+    return value;
+  }
+
+  public SSALegacyMatcherSpec setValue(String value) {
+    this.value = value;
+    return this;
+  }
+}

operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/ssalegacymatcher/ServiceDependentResource.java

@@ -0,0 +1,61 @@
+package io.javaoperatorsdk.operator.sample.ssalegacymatcher;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import io.fabric8.kubernetes.api.model.Service;
+import io.javaoperatorsdk.operator.SSAWithLegacyMatcherIT;
+import io.javaoperatorsdk.operator.api.reconciler.Context;
+import io.javaoperatorsdk.operator.processing.dependent.kubernetes.CRUDKubernetesDependentResource;
+import io.javaoperatorsdk.operator.processing.dependent.kubernetes.GenericKubernetesResourceMatcher;
+import io.javaoperatorsdk.operator.processing.dependent.kubernetes.KubernetesDependent;
+
+import static io.javaoperatorsdk.operator.ReconcilerUtils.loadYaml;
+
+@KubernetesDependent
+public class ServiceDependentResource
+    extends CRUDKubernetesDependentResource<Service, SSALegacyMatcherCustomResource> {
+
+  public static AtomicInteger createUpdateCount = new AtomicInteger(0);
+
+  public ServiceDependentResource() {
+    super(Service.class);
+  }
+
+  @Override
+  protected Service desired(SSALegacyMatcherCustomResource primary,
+      Context<SSALegacyMatcherCustomResource> context) {
+
+    Service service = loadYaml(Service.class, SSAWithLegacyMatcherIT.class, "service.yaml");
+    service.getMetadata().setName(primary.getMetadata().getName());
+    service.getMetadata().setNamespace(primary.getMetadata().getNamespace());
+    Map<String, String> labels = new HashMap<>();
+    labels.put("app", "deployment-name");
+    service.getSpec().setSelector(labels);
+    return service;
+  }
+
+  @Override
+  public Result<Service> match(Service actualResource, SSALegacyMatcherCustomResource primary,
+      Context<SSALegacyMatcherCustomResource> context) {
+    return GenericKubernetesResourceMatcher.match(this, actualResource, primary, context,
+        true, false, false);
+  }
+
+  // override just to check the exec count
+  @Override
+  public Service update(Service actual, Service target, SSALegacyMatcherCustomResource primary,
+      Context<SSALegacyMatcherCustomResource> context) {
+    createUpdateCount.addAndGet(1);
+    return super.update(actual, target, primary, context);
+  }
+
+  // override just to check the exec count
+  @Override
+  public Service create(Service target, SSALegacyMatcherCustomResource primary,
+      Context<SSALegacyMatcherCustomResource> context) {
+    createUpdateCount.addAndGet(1);
+    return super.create(target, primary, context);
+  }
+}