Add docs, whats-new entry and author tags for container lifecycle metrics

- Add reference docs section in micrometer.adoc
- Add whats-new entry linking to ref docs
- Add @author Vineeth Yelagandula to modified classes

Signed-off-by: Vineeth <vineeth>

Author: Vineeth

spring-kafka-docs/src/main/antora/modules/ROOT/pages/kafka/micrometer.adoc

@@ -93,6 +93,26 @@ This class is a super for the mentioned above `MicrometerConsumerListener`, `Mic
 However, it can be used for any Kafka client use-cases.
 The class needs to be extended and its `bindClient()` and `unbindClient()` API have to be called to connect Kafka client metrics with a Micrometer collector.
 
+
+[[monitoring-container-lifecycle]]
+== Monitoring Listener Container Lifecycle
+
+Starting with version 4.1.0, the listener container will automatically create and update Micrometer ``Counter``s for container start and stop events, if `Micrometer` is detected on the classpath, and a single `MeterRegistry` is present in the application context.
+The counters can be disabled by setting the ``ContainerProperty``'s `micrometerEnabled` to `false`.
+
+Two counters are maintained - one for container start events and one for container stop events.
+
+The counters are named as follows:
+
+* `spring.kafka.container.start.count` - incremented each time the container is started
+* `spring.kafka.container.stop.count` - incremented each time the container is stopped (including abnormal stops)
+
+Both counters have the following tag:
+
+* `name` : (container bean name)
+
+This feature is useful for monitoring container restarts, detecting unexpected stops, and tracking the lifecycle of listener containers in production environments.
+
 [[observation]]
 == Micrometer Observation
 

spring-kafka-docs/src/main/antora/modules/ROOT/pages/whats-new.adoc

@@ -7,6 +7,12 @@
 This section covers the changes made from version 4.0 to version 4.1.
 For changes in earlier versions, see xref:appendix/change-history.adoc[Change History].
 
+[[x41-container-lifecycle-metrics]]
+=== Container Lifecycle Metrics
+
+The listener container now automatically tracks start and stop counts using Micrometer counters (`spring.kafka.container.start.count` and `spring.kafka.container.stop.count`), tagged with the container bean name.
+See xref:kafka/micrometer.adoc#monitoring-container-lifecycle[Monitoring Listener Container Lifecycle] for more information.
+
 [[x41-kafka-listener-ack-mode]]
 === `@KafkaListener` Changes
 

spring-kafka/src/main/java/org/springframework/kafka/listener/AbstractMessageListenerContainer.java

@@ -73,6 +73,7 @@
  * @author Sanghyeok An
  * @author Lokesh Alamuri
  * @author Christian Fredriksson
+ * @author Vineeth Yelagandula
  */
 public abstract class AbstractMessageListenerContainer<K, V>
 		implements GenericMessageListenerContainer<K, V>, BeanNameAware, ApplicationEventPublisherAware,

spring-kafka/src/main/java/org/springframework/kafka/listener/KafkaMessageListenerContainer.java

@@ -179,6 +179,7 @@
  * @author Jinhui Kim
  * @author Minchul Son
  * @author Youngjoo Kim
+ * @author Vineeth Yelagandula
  */
 public class KafkaMessageListenerContainer<K, V> // NOSONAR line count
 		extends AbstractMessageListenerContainer<K, V> implements ConsumerPauseResumeEventPublisher {