/usr/lib/jvm/java-1.5.0-gcj-6-amd64/lib/libjavamath.so is in libgcj17 6.3.0-18+deb9u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/jvm/java-1.5.0-gcj-6-amd64/lib/../../../x86_64-linux-gnu/gcj-6-17/libjavamath.so