/usr/lib/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/kde5wallet@guillermo.molina is in xul-ext-kwallet5 1.3-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/../../../xul-ext/kwallet5