v2.9.0

Change log:

7a3223d Upgrade Versions; Prepare for Release
295b68c GH-2357: Fix Sonar Issues
128372f GH-2357: Switch to CompletableFuture
a4ee066 GH-2355: Add ManualAckListenerErrorHandler (#2356)
e682c87 GH-2350: Fix Paused Partitions After Rebalance
2732303 GH-2344: AggReplyingKT Support Custom Correlation
b1d97b9 GH-2345: Fix Possible NPE in KafkaAdmin
4e6d59c Sonar Fixes
e579c62 Fix for Java 8 compatibility
dd981e1 GH-2239: Fix Boot AutoConfiguration
15e5668 GH-2340: Fix Retrying Batch Error Handling
e220b17 Sonar Fixes
11e03c9 GH-2262: Fix Possible NPE
f7cbbfe Sonar Fixes