/usr/share/jetty8/lib/jetty-plus-8.1.19.v20160209.jar is in libjetty8-extra-java 8.1.19-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/jetty8/lib/../../java/jetty8-plus.jar
/usr/share/jetty8/lib/../../java/jetty8-plus.jar