How to test file uploads in Play Framework [Java]

Working on MEDinar, we are doing unit test for test our app. One of the scenario is when users upload their slides. We need to check if everything works. But the problem is I could not find a working example in Java how to test file upload. So after digging and reading few examples how to do it in Scala

https://groups.google.com/forum/#!msg/play-framework/UVi2kFxNoiE/VzQz4o8Hao4J
http://stackoverflow.com/questions/15133794/writing-a-test-case-for-file-uploads-in-play-2-1-and-scala

I developed a working solution for Java. We have a controller action

and code to test it