Added to build.sbt file this line:
libraryDependencies += "org.json4s" %% "json4s-jackson" % "3.2.11"
And i can't see that the library is added. Maybe i need to do some build to this file?
Did you do an SBT refresh?
You do that by clicking on the right sidebar, where it says "Sbt" and then in the top-left corner of the opened tab, there's a refresh button.