Previously, the `ApplicationEventListeningMessageProducer` accepted
all `ApplicationEvent`'s and than filtered them.
This caused some `ApplicationEventMulticaster.retrieverCache` overhead.
* Improve `ApplicationEventListeningMessageProducer` to `implements SmartApplicationListener`.
This allows filtering earlier on first the appropriate `ApplicationEvent`
using `ApplicationEventListeningMessageProducer#supportsEventType`
and caching the `ApplicationListener` only for that `ApplicationEvent`.
* Re-register `ApplicationEventListeningMessageProducer` in the `ApplicationEventMulticaster`
when `ApplicationEventListeningMessageProducer#setEventTypes` is invoked
to clear the `ApplicationEventMulticaster.retrieverCache`.
* Move `org.springframework.integration.gemfire.inbound.SpelMessageProducerSupport` to core `ExpressionMessageProducerSupport`.
* Add test for the new logic int `ApplicationEventListeningMessageProducer` and its behavior with respect to the `ApplicationEventMulticaster.retrieverCache`.
JIRA: https://jira.springsource.org/browse/INT-2935
INT-2935: EMPS JavaDoc & AELMP ReadWriteLock
INT-2935: AELMP#eventTypes changing 'barrier'
INT-2935: avoid 'eventTypes' mutation afterwards
INT-2935: Polishing according PR comments
INT-2935: Fix NPE in the `setEventTypes`
Minor Polishing
Polish java docs/comments
Remove compiler warnings
116f4934c1