/usr/lib/jvm/java-1.5.0-gcj-4.6/bin/javac is in gcj-4.6-jdk 4.6.3-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/jvm/java-1.5.0-gcj-4.6/bin/../../../../bin/ecj
/usr/lib/jvm/java-1.5.0-gcj-4.6/bin/../../../../bin/ecj