/usr/lib/jvm/java-1.5.0-gcj-5-amd64/src.zip is in gcj-5-source 5.3.1-14ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/jvm/java-1.5.0-gcj-5-amd64/../../../share/java/libgcj-src-5.zip
/usr/lib/jvm/java-1.5.0-gcj-5-amd64/../../../share/java/libgcj-src-5.zip