sub-bar label position in stacked horizontal bar chart

hey there,

i'm trying to create a stacked bar chart with labels' positions configured for each segment.

i have a jsbin [here](https://jsbin.com/tukequhanu/edit?html,js,output).

this is what it looks like now:


my ideal solution would be to have the sub-bar's respective labels aligned:
* on the leftmost boundary of the leftmost sub-bar,
* on the rightmost boundary of the rightmost sub-bar,
* centered for the sub-bars in between


but i'd also be happy just having the labels centered inside each sub-bar.

i've gone through the reference material as well as examples and not found any indication that c3 has specialized API for positioning sub-bar labels.

can this be accomplished with some workaround?

thanks in advance.