GH-756: Doc polishing for the previous commit

Author: garyrussell

spring-kafka/src/main/java/org/springframework/kafka/annotation/KafkaListener.java

@@ -187,15 +187,19 @@
 	String beanRef() default "__listener";
 
 	/**
-	 * Override the container factory's {@code concurrency} setting for this listener.
-	 * May be a property placeholder or SpEL expression that evaluates to an integer.
+	 * Override the container factory's {@code concurrency} setting for this listener. May
+	 * be a property placeholder or SpEL expression that evaluates to a {@link Number}, in
+	 * which case {@link Number#intValue()} is used to obtain the value.
 	 * @return the concurrency.
 	 * @since 2.2
 	 */
 	String concurrency() default "";
 
 	/**
-	 * Set to true or false, to override the default setting in the container factory.
+	 * Set to true or false, to override the default setting in the container factory. May
+	 * be a property placeholder or SpEL expression that evaluates to a {@link Boolean} or
+	 * a {@link String}, in which case the {@link Boolean#parseBoolean(String)} is used to
+	 * obtain the value.
 	 * @return true to auto start, false to not auto start.
 	 * @since 2.2
 	 */

spring-kafka/src/main/java/org/springframework/kafka/annotation/KafkaListenerAnnotationBeanPostProcessor.java

@@ -657,8 +657,9 @@ else if (resolved instanceof Number) {
 			return ((Number) resolved).intValue();
 		}
 		else {
-			throw new IllegalStateException("The [" + attribute + "] must resolve to a String. "
-					+ "Resolved to [" + resolved.getClass() + "] for [" + value + "]");
+			throw new IllegalStateException(
+					"The [" + attribute + "] must resolve to an Number or a String that can be parsed as an Integer. "
+							+ "Resolved to [" + resolved.getClass() + "] for [" + value + "]");
 		}
 	}
 
@@ -672,8 +673,9 @@ else if (resolved instanceof String) {
 			return Boolean.parseBoolean(s);
 		}
 		else {
-			throw new IllegalStateException("The [" + attribute + "] must resolve to a Boolean. "
-					+ "Resolved to [" + resolved.getClass() + "] for [" + value + "]");
+			throw new IllegalStateException(
+					"The [" + attribute + "] must resolve to a Boolean or a String that can be parsed as a Boolean. "
+							+ "Resolved to [" + resolved.getClass() + "] for [" + value + "]");
 		}
 	}
 

src/reference/asciidoc/kafka.adoc

@@ -777,9 +777,23 @@ public class KafkaConfig {
 Notice that to set container properties, you must use the `getContainerProperties()` method on the factory.
 It is used as a template for the actual properties injected into the container.
 
-Starting with _version 2.1.1_, it is now possible to set the `client.id` property for consumers created by the annotation.
+Starting with version 2.1.1, it is now possible to set the `client.id` property for consumers created by the annotation.
 The `clientIdPrefix` is suffixed with `-n` where `n` is an integer representing the container number when using concurrency.
 
+Starting with version 2.2, you can now override the container factory's `concurrency` and `autoStartup` properties using properties on the annotation itself.
+The properties can be simple values, property placeholders or SpEL expressions.
+
+====
+[source, java]
+----
+@KafkaListener(id = "myListener", topics = "myTopic",
+        autoStartup = "${listen.auto.start:true}", concurrency = "${listen.concurrency:3}")
+public void listen(String data) {
+    ...
+}
+----
+====
+
 You can also configure POJO listeners with explicit topics and partitions (and, optionally, their initial offsets):
 
 [source, java]

src/reference/asciidoc/whats-new.adoc

@@ -31,6 +31,12 @@ Batch listeners can optionally receive the complete `ConsumerRecords<?, ?>` obje
 
 See <<batch-listeners>> for more information.
 
+==== @KafkaListener Changes
+
+You can now override the `concurrency` and `autoStartup` properties of the listener container factory by setting properties on the annotation.
+
+See <<kafka-listener-annotation>> for more information.
+
 ==== Header Mapping Changes
 
 Headers of type `MimeType` and `MediaType` are now mapped as simple strings in the `RecordHeader` value.