Theme JSON: Card Bold Font

Hello, 

With PBI Novermber update Microsoft updated format pane adding new card property - Bold.

I'm wondering how to include this into custom JSON theme? I want to set the formatting of the Data Label, to make it Arial Bold. Below is the card section of my JSON code. Any assistance would be greatly appreciated.  Thanks!

{
  "name": "Card-1",
  "visualStyles": {
    "*": {
      "*": {
        "*": [
          {
            "color": {
              "solid": {}
            }
          }
        ]
      }
    },
    "card": {
      "*": {
        "labels": [
          {
            "show": true,
            "color": {
              "solid": {
                "color": "#000000"
              }
            },
            "fontSize": 40,
            "fontFamily": "Arial"
          }
        ]
      }
    }
  }
}