When just importing the ftp example as a maven project, I ran into the issue of a slf4j version discrepancy described here:
http://www.slf4j.org/faq.html#IllegalAccessError
This is solved by adding the specific version dependency of `slf4j-api`.
* Add the specific `slf4j-api` dependency to the Gradle script
* Change the dependency scope for `slf4j-` impl to the `runtime`.
* Regenerate POMs