Change log:
49b1b69 (HEAD -> 5.4.x) Fix raw type in the MqttAdapterTests
c3eda50 Upgrade to spring-amqp 2.3.4
628035c Upgrade dependencies
c880a34 GH-3450: Expose PubSub requireSubscribers option (#3459)
040fa70 GH-3455: default MqttMessConv.toMessageBuilder()
732a1b8 GH-3454: From MQTT conversion error - to error ch (#3456)
ebe79ae GH-3452: Warn Publisher.onError in NullChannel (#3453)
5ed8c11 Subscribe to Publisher in the NullChannel (#3448)
1bb58f4 Add https://plugins.gradle.org/m2 repo into build
a79c245 GH-3445: Fix JdbcLock for IllegalMonitorStateEx