I'm trying to set the property showLegendKey and the API doesn't have that ability.

I saved my PPTX in 2 locations, one with Legend Key checked and one without. Extracted both archives and found that chart5.xml differed. The following formatted snippet XML is the difference.

<c:dLblPos val="outEnd" />
<c:showLegendKey val="1" /> <!-- this is the only difference among the other settings -->
<c:showVal val="0" />
<c:showCatName val="0" />
<c:showSerName val="0" />
<c:showPercent val="1" />
<c:showBubbleSize val="0" />
<c:showLeaderLines val="0" />

How difficult would it be to add this? Or has is already been added?