fix: Controller annotation is not mandatory for default configuration

Author: metacosm

operator-framework/src/main/java/io/javaoperatorsdk/operator/config/runtime/AnnotationConfiguration.java

@@ -5,17 +5,18 @@
 import io.javaoperatorsdk.operator.api.Controller;
 import io.javaoperatorsdk.operator.api.ResourceController;
 import io.javaoperatorsdk.operator.api.config.ControllerConfiguration;
+import java.util.Optional;
 import java.util.Set;
 
 public class AnnotationConfiguration<R extends CustomResource>
     implements ControllerConfiguration<R> {
 
   private final ResourceController<R> controller;
-  private final Controller annotation;
+  private final Optional<Controller> annotation;
 
   public AnnotationConfiguration(ResourceController<R> controller) {
     this.controller = controller;
-    this.annotation = controller.getClass().getAnnotation(Controller.class);
+    this.annotation = Optional.ofNullable(controller.getClass().getAnnotation(Controller.class));
   }
 
   @Override
@@ -30,16 +31,13 @@ public String getCRDName() {
 
   @Override
   public String getFinalizer() {
-    final String annotationFinalizerName = annotation.finalizerName();
-    if (!Controller.NULL.equals(annotationFinalizerName)) {
-      return annotationFinalizerName;
-    }
-    return ControllerUtils.getDefaultFinalizerName(getCRDName());
+    return annotation.map(Controller::finalizerName).filter(String::isBlank)
+        .orElse(ControllerUtils.getDefaultFinalizerName(getCRDName()));
   }
 
   @Override
   public boolean isGenerationAware() {
-    return annotation.generationAwareEventProcessing();
+    return annotation.map(Controller::generationAwareEventProcessing).orElse(true);
   }
 
   @Override
@@ -49,7 +47,7 @@ public Class<R> getCustomResourceClass() {
 
   @Override
   public Set<String> getNamespaces() {
-    return Set.of(annotation.namespaces());
+    return Set.of(annotation.map(Controller::namespaces).orElse(new String[]{}));
   }
 
   @Override