In Dash manifest, how to insert duration into the segmentTemplate or pass the segment duration in segment requests?

Question

Take the following SegmentTemplate as an example with varying sizes of segments.

<SegmentTemplate timescale="30000" media="155_video_1_2_$Time$.mp4?m=1545421124" initialization="155_video_1_2_init.mp4?m=1545421124" startNumber="710">
  <SegmentTimeline>
       <S t="255197799" d="360360" r="8"/>
       <S t="258441039" d="334334"/>
  </SegmentTimeline>
</SegmentTemplate>

For each segment request, how do I pass in the varying size per segment request? In this example there should be 8 segments with duration=360360, and the final segment of duration=334334. Is there an attribute like $Duration$ or a way to pass in the end time of the segment?

This is for a backend ABR that transcodes video into smaller segments. And it'd be very useful to know when to stop if a manifest has varying sizes of segments.

I have looked into source code of Shaka player and it doesn't appear that there are any attributes other than $(RepresentationID|Number|Bandwidth|Time)$