Mouse event data for 'pie' and 'sankey' plots doesn't return curveNumber or pointNumber #1875

An example of sankey plot, view console for hover event output:
https://codepen.io/monfera/pen/VbKrXM

The hover event for a sankey plot currently returns:

The hover event for a pie plot currently returns (from Dash):

Both types of eventData don't include curveNumber or pointNumber.

In the case that there is more than one pie or sankey trace per plot it isn't possible to identify which trace triggered the mouse event without having access to the curveNumber and ideally the pointNumber as well.

From what I was able to find I think the issue stems from here: