There should be no more need for Java 6 on the Jenkins slaves. We should get rid of it on all slaves:
- update puppet manifest to no more install openjdk-6-* https://gerrit.wikimedia.org/r/220098
- verify Jenkins Java configuration for jobs
- Global default JVM -- Uses java from PATH
- Maven jobs and others (JVM version might be hardcoded in JJB) -- Use either Default or JDK 7
- verify Jenkins slaves are started with java 7 -- switched the Precise ones by disconnecting/reconnecting
- purge java 6 (puppet ensure => absent ?) -- purged manually
- make sure Java related utilities are using Java 7 (jmap etc).