/usr/share/jetty8/lib/jsp/javax.servlet.jsp.jstl.jar is in libjetty8-extra-java 8.1.16-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/jetty8/lib/jsp/../../../java/jstl1.1.jar
/usr/share/jetty8/lib/jsp/../../../java/jstl1.1.jar