vega lite -在图表中保留空的日期/时间

{
  "data": {
    "values": [
      {"date": "2022-01-01", "value": 10},
      {"date": "2022-01-03", "value": 15},
      {"date": "2022-01-05", "value": 8}
    ]
  },
  "transform": [
    {
      "calculate": "toDate(datum.date)",
      "as": "parsed_date"
    },
    {
      "sequence": {
        "start": min(parseDateTime("2022-01-01")),
        "stop": max(parseDateTime("2022-01-05")),
        "step": 1,
        "unit": "day"
      },
      "as": "all_dates"
    },
    {
      "lookup": "parsed_date",
      "from": {"data": {"values": [{"parsed_date": null}]}},
      "key": "parsed_date",
      "fields": ["parsed_date", "value"],
      "as": ["parsed_date", "value"]
    }
  ],
  "mark": "line",
  "encoding": {
    "x": {"field": "parsed_date", "type": "temporal"},
    "y": {"field": "value", "type": "quantitative"}
  }
}