Change log:
c9ffc7a Upgrade to SF-4.3.20
be0cb65 GH-881: Null check in closeProducers()
c2a125d GH-842: Fix NPEs in KafkaListenerAnnotationBPP (#864)
a50a2a9 GH-859: Fix nested transactions
9c9a200 GH-834: Remove transactional producers
7517916 GH-804: EmbedKafkaCtxCustom add hashCode & equals
