found with

    git grep -A2 -nP '!.*\.empty()' | grep -B1 -w clear

Change-Id: I87013eab9c6988048b891d20577e1f7efbce1b6c
Reviewed-on: https://gerrit.libreoffice.org/61295
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>