JIRA: https://jira.spring.io/browse/INT-4305
The `File.renameTo()` operation may fail, therefore the content of the
local file isn't changed, but since we change `setLastModified()` anyway,
this file might be eligible for local polling.
So, we end up with the same content from local file in a new message,
meanwhile we expect a new content from the remote file
* Check the `File.renameTo()` result and attempt to `delete()`
for existing local file
* When file isn't renames remove the remote file from the `filter` to let
it be transferred one more time on the next poll.
The local file might be opened for processing, so this way we postpone a fresh
remote file for the future poll rounds
* Modify `copyFileToLocalDirectory()` to return `boolean` to reflect the fact of copy.
This way we check the real number of transferred files
**Cherry-pick to 4.3.x**
Do not transfer remote file if we can't remove local one
Polishing Log Messages
Conflicts:
spring-integration-file/src/main/java/org/springframework/integration/file/remote/synchronizer/AbstractInboundFileSynchronizer.java
spring-integration-file/src/test/java/org/springframework/integration/file/remote/synchronizer/AbstractRemoteFileSynchronizerTests.java
spring-integration-ftp/src/test/java/org/springframework/integration/ftp/dsl/FtpTests.java
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