v6.0.8

Change log:
59a88c2 Update dependencies; prepare for release
45bbaf9 Streamline UUIDConverter
52952a4 Reduce log noise for AbstractCorrelatingMH
7d73e52 GH-8745: Add RFT.shouldMarkSessionAsDirty() (#8759)
31de789 IntFlowContext: Fix missed import for @Nullable
680acfb GH-8750: Add @Nullable to getRegistrationById()
f64cda7 GH-8754: MessageBuilder: enhance @Nullable
96bea49 GH-8748: JDBC locks: use READ_COMMITTED isolation (#8749)
5489b15 Fix maxMessagesPerPoll for SourcePollingChAdapter (#8747)
18aff78 Fix JMS Inbound Endpoints for observation
0b7c769 Fix ThreadSPropagationChInterceptor for stacking (#8735)
e2ccd10 Fix Checkstyle violation in the JdbcLockRegistry
e8cf812 GH-8730: Fix isAcquiredInThisProcess to use localLock
d8a4765 Fix PostgresSubscribableChannel.notifyUpdate()
2a22bf8 GH-8720: Check MQTT topics if not empty strings
26fae85 GH-8692 Add createIndexes to MongoDbMessageStore