/usr/share/doc/libhsqldb1.9-java-doc/examples/hsqldb.jar is in libhsqldb-java-doc 2.2.9+dfsg-4ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libhsqldb1.9-java-doc/examples/../../../java/hsqldb.jar