@jaliss and I were recently wondering how to make sure that a module was compiled with JSDK 1.6 after we had upgraded the Java Version on our Macbooks.
Stackoverflow user mgregori just provided this solution (Thanks!):
In the file project/Build.scala, add the setting below if you want to compile with java 1.6 :
val main = play.Project(appName, appVersion, appDependencies).settings( // Force compilation in java 1.6 javacOptions in Compile ++= Seq("-source", "1.6", "-target", "1.6") )