New Blox Border Snippet

I cannot figure out where in the editor to place the border snippet code to keep my blox widget from using the system defaulted corner radius.  No matter where I place it the corners of the widget remain rounded.

{
  "spaceAround": "none|small|medium|large",
  "cornerRadius": "none|small|medium|large",
  "borderColor": "",
  "shadow": "none|light|medium|dark"
}