Comment indicated "If one of these fields is empty, the button is disabled",
let's stick to this.

Cherry-picked from 2ff595db

Change-Id: I99dd23339d888c33e7706935842a91f5da681ade
Reviewed-on: https://gerrit.libreoffice.org/19112Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>
(cherry picked from commit 3a3fb3c5)