JIRA: https://jira.spring.io/browse/INT-4344
The `FtpOutboundGateway` provides ctors without expression for remote path.
In this case it is treated as a `working directory` but only for the
`LS`, `NLST`, `PUT` and `MPUT` commands.
* Add assertion in the `AbstractRemoteFileOutboundGateway` to discard
configuration for all other commands when `expression` is `null`
**Cherry-pick to 4.3.x**
Conflicts:
spring-integration-file/src/main/java/org/springframework/integration/file/remote/gateway/AbstractRemoteFileOutboundGateway.java
Resolved.
7d24b8ec67