/usr/lib/x86_64-linux-gnu/libgcj-tools.so.12 is in libgcj12 4.6.3-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgcj-tools.so.12.0.0
/usr/lib/x86_64-linux-gnu/libgcj-tools.so.12.0.0