/usr/share/maven-repo/org/apache/lucene/lucene-demo/3.6.2/lucene-demo-3.6.2.jar is in liblucene3-contrib-java 3.6.2+dfsg-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/maven-repo/org/apache/lucene/lucene-demo/3.6.2/../../../../../../java/lucene3-demo-3.6.2.jar