GH-2262: Docs

Author: garyrussell

Diff for: spring-kafka-docs/src/main/asciidoc/changes-since-1.0.adoc

@@ -1,4 +1,20 @@
 [[migration]]
+=== What's New in 2.9 since 2.8
+
+[[x29-kafka-client]]
+==== Kafka Client Version
+
+This version requires the 3.2.0 `kafka-clients`.
+
+[[x29-eh-changes]]
+==== Error Handler Changes
+
+The `DefaultErrorHandler` can now be configured to pause the container for one poll and use the remaining results from the previous poll, instead of seeking to the offsets of the remaining records.
+See <<default-eh>> for more information.
+
+The `DefaultErrorHandler` now has a `BackOffHandler` property.
+See <<backoff-handlers>> for more information.
+
 === What's New in 2.8 Since 2.7
 
 This section covers the changes made from version 2.7 to version 2.8.

Diff for: spring-kafka-docs/src/main/asciidoc/kafka.adoc

@@ -5117,6 +5117,16 @@ The container commits any pending offset commits before calling the error handle
 
 If you are using Spring Boot, you simply need to add the error handler as a `@Bean` and Boot will add it to the auto-configured factory.
 
+[[backoff-handlers]]
+===== Back Off Handlers
+
+Error handlers such as the <<default-eh>> use a `BackOff` to determine how long to wait before retrying a delivery.
+Starting with version 2.9, you can configure a custom `BackOffHandler`.
+The default handler simply suspends the thread until the back off time passes (or the container is stopped).
+The framework also provides the `ContainerPausingBackOffHandler` which pauses the listener container until the back off time passes and then resumes the container.
+This is useful when the delays are longer than the `max.poll.interval.ms` consumer property.
+Note that the resolution of the actual back off time will be affected by the `pollTimeout` container property.
+
 [[default-eh]]
 ===== DefaultErrorHandler
 

Diff for: spring-kafka-docs/src/main/asciidoc/whats-new.adoc

@@ -21,4 +21,4 @@ See <<exactly-once>> and https://cwiki.apache.org/confluence/display/KAFKA/KIP-4
 ==== Global Single Embedded Kafka
 
 The embedded Kafka (`EmbeddedKafkaBroker`) can now be start as a single global instance for the whole test plan.
-See <<same-broker-multiple-tests>> for more information.
+See <<same-broker-multiple-tests>> for more information.