Custom connector icon border

The question I’m asking here might seem petty but I’m one thats always looking at the details.

Is there a way to set the icon border color of a custom connector built with the Connector Builder? The border is set by css so you don’t include it in your icon.png. It would be nice if there was a prop in index.json where you could set the hex color value.

In the documentation there is only details to make your icon 128x128 and less than 1MB, so maybe there is no option for the border.