Drawing Issue with Sandcastle

1. A concise explanation of the problem you're experiencing.
I'm seeing extraneous visual artifacts when drawing a polygon in the sandcastle.

2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.

https://cesiumjs.org/releases/1.48/AppsApps/Sandcastle/#c=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

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

I want to draw using the technique shown in the sandcastle without extraneous rendering artifacts.

4. The Cesium version you're using, your operating system and browser.

Cesium 1.48
Windows 10
Chrome

GIF:

I believe this is an artifact from common triangulation algorithms with self-intersecting polygons (see discussion here https://gis.stackexchange.com/questions/31109/why-are-self-intersecting-polygons-bad )

This describes a potential fix:

http://commaexcess.com/articles/7/concave-polygon-triangulation-shortcut

This might be a cool feature to contribute to Cesium!