/usr/share/maven-repo/com/google/protobuf/protobuf-java/debian/protobuf-java-debian.jar is in libprotobuf-java 2.6.1-1.3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/maven-repo/com/google/protobuf/protobuf-java/debian/../../../../../../java/protobuf-2.6.1.jar