Checkbox Tab Group

I’m attempting to make one of two checkboxes required.  This is my json:

  "checkboxTabs": [
    {
      "anchorIgnoreIfNotPresent": "true",
      "anchorString": "InsurerRequired_CKYes",
      "anchorUnits": "pixels",
      "anchorXOffset": "0",
      "anchorYOffset": "0",
      "tabId": "InsurerRequired_CKYes",
      "tabLabel": "Insurer Required",
      "tabGroupLabels": [
        "checkboxgroup1"
      ]
    },
    {
      "anchorIgnoreIfNotPresent": "true",
      "anchorString": "InsurerRequired_CKNo",
      "anchorUnits": "pixels",
      "anchorXOffset": "0",
      "anchorYOffset": "0",
      "tabId": "InsurerRequired_CKNo",
      "tabLabel": "Insurer Not Required",
      "tabGroupLabels": [
        "checkboxgroup1"
      ]
    }
  ],
  "tabGroups": [
    {
      "groupLabel": "checkboxgroup1",
      "minimumRequired": "1",
      "maximumAllowed": "1",
      "tabType": "tabgroup"
    }
  ]
 

The behavior is not changing with the tabGroups definition.  Both checkboxes are still optional, and both checkboxes can be selected.  I would appreciate any insight!

I did attempt to create radio buttons, but I got a runtime error.