Code review feedback

- Make annotation utils check for NONE more generic
- Move docs to whats-new.adoc
- Polish javadoc

Author: onobc

spring-integration-core/src/main/java/org/springframework/integration/util/MessagingAnnotationUtils.java

@@ -26,7 +26,6 @@
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.integration.annotation.EndpointId;
 import org.springframework.integration.annotation.Payloads;
-import org.springframework.integration.annotation.Poller;
 import org.springframework.messaging.MessagingException;
 import org.springframework.messaging.handler.annotation.Header;
 import org.springframework.messaging.handler.annotation.Headers;
@@ -71,12 +70,10 @@ public static <T> T resolveAttribute(List<Annotation> annotations, String name,
 	}
 
 	/**
-	 * Determines if the value of a named attribute from an annotation instance contains an actual value.
-	 * <p>It is considered to NOT contain a value if it is null, an empty string, an empty array, or a {@link Poller}
-	 * whose 'value' field is set to {@link ValueConstants#DEFAULT_NONE}.
-	 *
+	 * Determine if the value of a named attribute from an annotation instance contains an actual value.
 	 * @param annotationValue the value of the annotation attribute
-	 * @return whether {@code annotationValue} is set to a non-empty value
+	 * @return {@code false} when {@code annotationValue} is null, an empty string, an empty array, or any annotation
+	 * whose 'value' field is set to {@link ValueConstants#DEFAULT_NONE} - {@code true} otherwise
 	 */
 	public static boolean hasValue(Object annotationValue) {
 		if (annotationValue == null) {
@@ -90,8 +87,9 @@ public static boolean hasValue(Object annotationValue) {
 		if ((annotationValue instanceof String) && ObjectUtils.isEmpty(annotationValue)) {
 			return false;
 		}
-		// Poller with special 'none' value
-		if ((annotationValue instanceof Poller) && ValueConstants.DEFAULT_NONE.equals(((Poller) annotationValue).value())) {
+		// Annotation with 'value' set to special 'none' string
+		if ((annotationValue instanceof Annotation) &&
+				ValueConstants.DEFAULT_NONE.equals(AnnotationUtils.getValue((Annotation) annotationValue))) {
 			return false;
 		}
 		return true;

spring-integration-core/src/test/kotlin/org/springframework/integration/function/FunctionsTests.kt

@@ -58,7 +58,6 @@ import java.util.stream.Collectors
  * @author Artem Bilan
  * @author Chris Bono
  *
- *
  * @since 5.1
  */
 @SpringJUnitConfig

src/reference/asciidoc/changes-5.5-6.0.adoc

@@ -36,4 +36,21 @@ See <<./http.adoc#http,HTTP Support>> for more information.
 === RMI Removal
 
 The `spring-integration-rmi` module has been removed altogether after being deprecated in previous versions.
-There is no replacement: it is recommended to migrate to more secure network and application protocols, such as WebSockets, RSockets, gRPC or REST.
+There is no replacement: it is recommended to migrate to more secure network and application protocols, such as WebSockets, RSockets, gRPC or REST.
+
+[[x6.0-poller]]
+==== @Poller (Messaging Annotations)
+
+The messaging annotations
+
+- `@Aggregator`
+- `@BridgeFrom`
+- `@BridgeTo`
+- `@Filter`
+- `@InboundChannelAdapter`
+- `@Router`
+- `@ServiceActivator`
+- `@Splitter`
+- `@Transformer`
+
+used to contain a `Poller[]` attribute but now contain a single element. The array was only in place  to allow an empty default (no poller). This is now accomplished with a single element using the special value of `ValueConstants.DEFAULT_NONE`.