instance.dataViewMappings[0].categorical additionalProperty "xxxxx" exists in instance when not...

Hi,

When I save my capabilities.json file I get the following errors from the pbiviz command line tool:

 error  JSON  capabilities.json :  instance.dataViewMappings[0].categorical additionalProperty "names" exists in instance when not allowed
 error  JSON  capabilities.json :  instance.dataViewMappings[0].categorical additionalProperty "quadrants" exists in instance when not allowed
 error  JSON  capabilities.json :  instance.dataViewMappings[0].categorical additionalProperty "rings" exists in instance when not allowed

Here is the contents of said file:

{
  "dataRoles": [
    {
      "displayName": "Name",
      "name": "name",
      "kind": "Grouping"
    },
    {
      "displayName": "Quadrant",
      "name": "quadrant",
      "kind": "Grouping"
    },
    {
      "displayName": "Ring",
      "name": "ring",
      "kind": "Grouping"
    }
  ],
  "dataViewMappings": [
    {
      "categorical": {
        "names": {
          "for": {
            "in": "name"
          }
        },
        "quadrants": {
          "for": {
            "in": "quadrant"
          }
        },
        "rings": {
          "for": {
            "in": "ring"
          }
        }
      }
    }
  ]
}

I'm brand new to custom visual development so I don't really know where to start in trying to debug this. Can anyone spot where I'm going wrong with this?

For context, I'm basically trying to create a similar visual to this (click on one of the four boxes), i.e. plotting points, each of which has a name, a quadrant and a ring.

Thanks!