JIRA: https://jira.spring.io/browse/INT-4356
**Cherry-pick to 4.3.x**
Address PR comments:
* Remove unused variable in the test case
* Add string-based SpEL setters to the `AbstractInboundFileSynchronizer`
* Fix `@since` in the `FileTransferringMessageHandler` to the proper version
Conflicts:
spring-integration-file/src/main/java/org/springframework/integration/file/remote/handler/FileTransferringMessageHandler.java
spring-integration-file/src/main/java/org/springframework/integration/file/remote/synchronizer/AbstractInboundFileSynchronizer.java
Resolved.
442d6c6a90