Renaming function from 'IsFoo' to 'GetFoo'

Change-Id: If4b4de730a5bc1825ddd1430fe68a31eb423bf50
Reviewed-on: https://gerrit.libreoffice.org/7127
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>