The release of Java update 29 from Oracle marks not only security updates, but a change to the licensing, removing Debian's ability to distribute the non-free JVM. The clause in the Java license under which we were able to distribute Java, the DLJ, has been removed. As a result, the sun-java6 package is no longer suitable for the archive, and has been removed, as documented in Debian Bug #646524 [2]. Sylvestre Ledru suggests [3] that sun-java6 installs be migrated to openjdk, the open-source alternative, using the following command: "apt-get --purge remove sun-java6-jre && apt-get install openjdk-7-jre" Kai Wasserbäch has also been pointed out elsewhere [4] that this upgrade path might not be suitable for all Java programs, and special attention should be paid to re-testing installed Java applications on OpenJDK.
2 : http://bugs.debian.org/646524
3 : http://sylvestre.ledru.info/blog/sylvestre/2011/10/25/removal_of_sun_java6_from_debian
4 : http://www.carbon-project.org/Removal_of_sun_java6_and_ElsterOnline.html