title: Error:scalac: 'jvm-1.9' is not a valid choice for '-target'
body: <p>Created a new clean Scala project using Gradle.</p>
  
  <p>This is the only dependency:</p>
  
  <pre><code>compile "org.scala-lang:scala-library:2.12.4"
  </code></pre>
  
  <p>When building on the command line <code>./gradlew build</code> works perfectly fine. However, when using IntelliJ it gives me this warning:</p>
  
  <pre><code>Error:scalac: 'jvm-1.9' is not a valid choice for '-target'
  Error:scalac: bad option: '-target:jvm-1.9'
  </code></pre>
  
  <p>I have both the JDK with java 8 and 9 installed, but I'm currently using JDK 1.8. But I'm not sure if that's related.</p>