JIRA: https://jira.spring.io/browse/INT-3691 - create new core interfaces `ListenableMetadataStore` and `MessageStoreListener`; - create new module `spring-integration-zookeeper`; - add `ZookeeperMetadataStore` implementation Polishing Polishing - moved classes into core/test where necessary, including conversion methods - properly renamed `MetadataStoreListenerAdapter`