already in its ctor
which changed since...
commit 9009663deb
Date: Sun Feb 26 22:48:06 2017 +0100
tdf#83257 [API-CHANGE] Pivot chart implementation
which defers it, take a probably safely backportable approach here to
fix it.
Change-Id: I1863791af7ae737f337993833a9cf1429a3a8028
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/132286
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>