Fixes: https://github.com/spring-projects/spring-integration/issues/2820 The current `FtpRemoteFileTemplate.exists()` implementation obtains a `Session` for the `NLST_AND_DIRS` mode, but doesn't close it. * Fix the `FtpRemoteFileTemplate.exists()` method to delegate to `super` for the proper interaction with a `Session` **Cherry-pick to 5.1.x, 5.0.x & 4.3.x**