/usr/share/jetty/lib/jsp-2.1/slf4j-api.jar is in libjetty-extra-java 6.1.26-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/jetty/lib/jsp-2.1/../../../java/slf4j-api.jar
/usr/share/jetty/lib/jsp-2.1/../../../java/slf4j-api.jar