I am trying to customize an EChart Sankey and would like to add a label to the different levels.

For Example, I want to add the red text in this image. What options do I need to change.

The levels documentation seems to imply that this would be correct option however there doesn’t seem to be a way to add a label for the entire level.

https://echarts.apache.org/en/option.html#series-sankey.levels