/usr/lib/jvm/java-6-openjdk-amd64/src.zip is in openjdk-6-jdk 6b41-1.13.13-0ubuntu0.12.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/jvm/java-6-openjdk-amd64/../java-6-openjdk-common/src.zip