当系列没有相同的时间值时，如何在工具提示中显示所有系列

Question

我有一个显示多个时间序列的图表。不同的时间序列不会同时采样。有什么方法可以在工具提示中显示所有系列吗？在示例中，您可以看到所有序列都同时采样在两个前两个点的工具提示中。对于其余的点，仅包括1个系列。

var myChart = echarts.init(document.getElementById('main'));

var series = [{
    "name": "sensor 1",
    "data": [{
        "value": [
          "2019-02-20T11:47:44.000Z",
          22.2
        ]
      },
      {
        "value": [
          "2019-02-20T12:03:02.000Z",
          22.1
        ]
      },
      {
        "value": [
          "2019-02-20T12:18:19.000Z",
          22.15
        ]
      },
      {
        "value": [
          "2019-02-20T12:33:36.000Z",
          22.2
        ]
      },
      {
        "value": [
          "2019-02-20T12:48:53.000Z",
          22.15
        ]
      }
    ],
    "type": "line"
  },
  {
    "name": "sensor 2",
    "data": [{
        "value": [
          "2019-02-20T11:47:44.000Z",
          23.2
        ]
      },
      {
        "value": [
          "2019-02-20T12:03:02.000Z",
          23.1
        ]
      },
      {
        "value": [
          "2019-02-20T12:22:19.000Z",
          24.15
        ]
      },
      {
        "value": [
          "2019-02-20T12:39:36.000Z",
          21.2
        ]
      },
      {
        "value": [
          "2019-02-20T12:52:53.000Z",
          20.15
        ]
      }
    ],
    "type": "line"
  }
]

var option = {
  legend: {},
  tooltip: {
    trigger: 'axis',
  },
  xAxis: {
    type: 'time'
  },
  yAxis: {
    scale: true
  },
  series: series,
};

myChart.setOption(option);

<script src="https://cdnjs.cloudflare.com/ajax/libs/echarts/4.0.4/echarts.min.js"></script>

<div id="main" style="width: 500px;height:400px;"></div>