Why does chart_StarOffice_XML_Chart not have a DetectService?

With the current Keynote filter's detectVersionFromInput (libetonyek 
src/lib/KEYDocument.cpp) being too imprecise and causing 
JunitTest_chart2_unoapi to fail when that tries to load 
chart2/qa/unoapi/testdocuments/TransparencyChart.sxs, I (re-?) 
discovered that 
filter/source/config/fragments/types/chart_StarOffice_XML_Chart.xcu does 
not specify a DetectService.

In TypeDetection::queryTypeByDescriptor 
(filter/source/config/cache/typedetection.cxx) 
chart_StarOffice_XML_Chart is sorted to the head of lFlatTypes due the 
matching "sxs" extension, but in the following 
TypeDetection::impl_detectTypeFlatAndDeep, the missing DetectionService 
for chart_StarOffice_XML_Chart causes impress_AppleKeynote, which comes 
later in lFlatTypes but does have an (over-eager) DetectService, to win.

Does anybody happen to have any insight why there is no DetectService 
for chart_StarOffice_XML_Chart (when the dozen other 
filter/source/config/fragments/types/*_StarOffice_*.xcu each specify one)?

Stephan