/usr/share/java/logback-core.jar is in liblogback-java 1:1.1.2-1+deb8u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/java/logback-core-1.1.2.jar
/usr/share/java/logback-core-1.1.2.jar