slave agent fails to start due to openjdk version

Hi,

the jenkins slave agent fails to start with the following error message:
Exception in thread "main" java.lang.UnsupportedClassVersionError: hudson/remoting/Launcher : Unsupported major.minor version 51.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:648)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:206)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:325)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:296)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:270)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:406)

This is due to openjdk-6 which seems to be no more supported by the jenkins slave agent.
package versions:
- openjdk-6-jre 6b40-1.13.12-0ubuntu0.12.04.2
- jenkins-slave 1.424.6+dfsg-1ubuntu0.2

upgrading to openjdk-8 solves this issue.
tried with: openjdk-8-jre 8u111-b14-3~12.04

Eric