You can always specify the JDK version for your app when deploying:
bees app:deploy -t play2 -R java_version=1.7
In this example - it is deploying a play 2 app and setting the version to Java 7 (1.6, 1.7 and 1.8 are currently available). For many things, Java 7 is, or should be, or will be the default - but if you are like me - you like to drive manual (stick) - and set it yourself so you know.
If you deploy a Java 7 app to a Java 6 container - you will likely see "major.minor" error in a stack trace - that is why. Switch to Java 7 and all will be good!