Merge branch 'all-multi-resource-es' of github.com:java-operator-sdk/java-operator-sdk into all-multi-resource-es

Author: csviri

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/MultiResourceOwner.java

@@ -5,7 +5,7 @@ public interface IDMapper<R> {
   String getID(R var1);
 
   /**
-   * Used If a polling event source handles only single secondary resource. See also docs for:
+   * Used if a polling event source handles only single secondary resource. See also docs for:
    * {@link ExternalResourceCachingEventSource}
    *
    * @return static id mapper, all resources are mapped for same id.

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

@@ -1,9 +1,25 @@
 package io.javaoperatorsdk.operator.processing.event.source;
 
+import java.util.Optional;
+import java.util.Set;
+
 import io.fabric8.kubernetes.api.model.HasMetadata;
-import io.javaoperatorsdk.operator.processing.MultiResourceOwner;
+import io.javaoperatorsdk.operator.processing.ResourceOwner;
 
 public interface ResourceEventSource<R, P extends HasMetadata> extends EventSource,
-    MultiResourceOwner<R, P> {
+    ResourceOwner<R, P> {
+
+  default Optional<R> getSecondaryResource(P primary) {
+    var resources = getSecondaryResources(primary);
+    if (resources.isEmpty()) {
+      return Optional.empty();
+    } else if (resources.size() == 1) {
+      return Optional.of(resources.iterator().next());
+    } else {
+      throw new IllegalStateException("More than 1 secondary resource related to primary");
+    }
+
+  }
 
+  Set<R> getSecondaryResources(P primary);
 }