ODF specifies that extension elements in a document are removed before
the validation. With our old implementation of the number format export
this could result in two number:text elements following each other.
According to the spec a number:text element may not follow another
number:text element.
The number:text element before loext:fill is actually not that
interesting so it makes more sense to make this one an extension
element.
Possible documents showing issues:
fdo45268-1.xlsx
fdo49150-1.xlsx
and many more
Change-Id: I3ad92b8a61a246b3dbc0132d9a2c367488a766d0
see https://gerrit.libreoffice.org/#/c/3367/
and Change-Id: I00c96fa77d04b33a6f8c8cd3490dfcd9bdc9e84a for details
Change-Id: I199a75bc4042af20817265d5ef85b1134a96ff5a
