docs: new event sources

Author: csviri

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

@@ -11,6 +11,18 @@
 import io.javaoperatorsdk.operator.processing.event.Event;
 import io.javaoperatorsdk.operator.processing.event.ResourceID;
 
+/**
+ * Base class for event sources with filtering and caching capabilities.
+ * <p>
+ * {@link #handleDelete(ResourceID)} - if the related resource is present in the cache it is
+ * removed. and event propagated. There is no event propagated if the resource is not in the cache.
+ * <p>
+ * {@link #handleEvent(Object, ResourceID)} - caches the resource if changed (or nto present
+ * before). Propagates an event if the resource is new or not equals to the one in the cache, and if
+ * accepted by the filter if one is present.
+ *
+ * @param <T> represents the resource (usually external non-kubernetes one) handled.
+ */
 public abstract class CachingFilteringEventSource<T> extends LifecycleAwareEventSource {
 
   private static final Logger log = LoggerFactory.getLogger(CachingFilteringEventSource.class);

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

@@ -20,6 +20,17 @@
 import io.javaoperatorsdk.operator.processing.event.source.ResourceEventAware;
 import io.javaoperatorsdk.operator.processing.event.source.controller.ResourceCache;
 
+/**
+ *
+ * Polls the supplier for each controlled resource registered. Resource is registered when created
+ * if there is no registerPredicate provided. If register predicate provided it is evaluated on
+ * resource create and/or update to register polling for the event source.
+ * <p>
+ * For other behavior see {@link CachingFilteringEventSource}
+ *
+ * @param <T> the resource polled by the event source
+ * @param <R> related custom resource
+ */
 public class PerResourcePollingEventSource<T, R extends HasMetadata>
     extends CachingFilteringEventSource<T>
     implements ResourceEventAware<R> {