text: [
    {
      "description": "validation of null and format",
      "schema": {"type": ["null", "string"], "format": "date-time"},
      "tests": [
        {
          "description": "a valid date-time string",
          "data": "1963-06-19T08:30:06.283185Z",
          "valid": true
        },
        {
          "description": "allow null",
          "data": null,
          "valid": true
        }
      ]
    }
  ]