/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/ is in xul-ext-gdata-provider 1:52.7.0+build1-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/OAuth2.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/gdataLogging.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/gdataRequest.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/gdataSession.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/gdataUtils.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/Calendar.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/Http.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/Loader.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/Preferences.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/Promise.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/PromiseExtras.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/PromiseUtils.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/Task.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/shim/Timer.jsm
/usr/lib/thunderbird-addons/extensions/{a62ef8ec-5fdc-40c2-873c-223b8a6925cc}/modules/timezoneMap.jsm