GH-650: Pause/Resume doc example

Resolves #650

Author: garyrussell

src/reference/asciidoc/kafka.adoc

@@ -1476,6 +1476,65 @@ However, the consumers might not have actually paused yet; `isConsumerPaused()`
 
 In addition, also since _2.1.5_, `ConsumerPausedEvent` s and `ConsumerResumedEvent` s are published with the container as the `source` property and the `TopicPatition` s involved in the `partitions` s property.
 
+This simple Spring Boot application demonstrates using the container registry to get a reference to a `@KafkaListener` method's container and pausing/resuming its consumers, as well as receiving the corresponding events.
+
+[source, java]
+----
+@SpringBootApplication
+public class Application implements ApplicationListener<KafkaEvent> {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args).close();
+    }
+
+    @Override
+    public void onApplicationEvent(KafkaEvent event) {
+        System.out.println(event);
+    }
+
+    @Bean
+    public ApplicationRunner runner(KafkaListenerEndpointRegistry registry,
+            KafkaTemplate<String, String> template) {
+        return args -> {
+            template.send("pause.resume.topic", "foo");
+            Thread.sleep(10_000);
+            System.out.println("pausing");
+            registry.getListenerContainer("pause.resume").pause();
+            Thread.sleep(10_000);
+            template.send("pause.resume.topic", "bar");
+            Thread.sleep(10_000);
+            System.out.println("resuming");
+            registry.getListenerContainer("pause.resume").resume();
+            Thread.sleep(10_000);
+        };
+    }
+
+    @KafkaListener(id = "pause.resume", topics = "pause.resume.topic")
+    public void listen(String in) {
+        System.out.println(in);
+    }
+
+    @Bean
+    public NewTopic topic() {
+        return new NewTopic("pause.resume.topic", 2, (short) 1);
+    }
+
+}
+----
+
+With results:
+
+[source]
+----
+partitions assigned: [pause.resume.topic-1, pause.resume.topic-0]
+foo
+pausing
+ConsumerPausedEvent [partitions=[pause.resume.topic-1, pause.resume.topic-0]]
+resuming
+ConsumerResumedEvent [partitions=[pause.resume.topic-1, pause.resume.topic-0]]
+bar
+----
+
 [[serdes]]
 ==== Serialization/Deserialization and Message Conversion