{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "txtContent": "=if(Number([$DueDate]) == 0, 'Blank Date' , if([$DueDate] < @now, 'Expired', 'Active'))",
  "attributes": {
    "class": "=if(Number([$DueDate]) == 0, 'sp-field-severity--warning' , if([$DueDate] < @now, 'sp-field-severity--blocked', 'sp-field-severity--good'))"
  }
}