Playframework: Integration tests in src/it/scala don't compile in IDEA

I have configured integration tests for a playframework project in scr/it/scala
like here:

They compile and execute fine with sbt, but the eclipse editor can not resolve the symbols, so I don't enjoy all
the niceties IDEA provides for scala.
How do I configure IDEA to accept this folder with the correct classpath.
The normal playframework tests in test/scala are fine.

thank you very much,