unused generated attributes

Change-Id: I6e838dfca60cff5dbcab1fa81d55a0774d749ef8
fix variable prefix

Change-Id: Id963e4dcfecefa0425a2fdfd61e0adbcd6995f0c
DOCX export: avoid empty attributes in paragraph shading

Change-Id: I4bdf3f2d7f2aee3ce735a52185e736a8861d85e4