🐛 [BUG]多图表下heatmap legend不展示

[shellphon]

🐛 Bug description

想在heatmap下给地图标注一些标记点，采用多图表方式，heatmap + dot ，但在示例中发现heatmap的图例不见了

📷 Step to reproduce

import { L7Plot } from '@antv/l7plot';

Promise.all([fetch('https://gw.alipayobjects.com/os/antfincdn/S2Pb%26549sG/20210723023614.json')
  .then((response) => response.json())])
  .then(([heat]) => {
    new L7Plot('container', {
      map: {
        type: 'amap',
        style: 'dark',
        zoom: 11.7,
        center: [120.19660949707033, 30.234747338474293],
        pitch: 0,
      },
      logo:false,
      plots: [
        {
          type: 'heatmap',
          zIndex: 1,
          source: {
          data: heat,
          parser: {
            type: 'geojson',
          },
        },
        size: {
          field: 'count',
          value: [0, 1],
        },
        style: {
          intensity: 2,
          radius: 15,
          opacity: 1,
          colorsRamp: [
            { color: 'rgba(33,102,172,0.0)', position: 0 },
            { color: 'rgb(103,169,207)', position: 0.2 },
            { color: 'rgb(209,229,240)', position: 0.4 },
            { color: 'rgb(253,219,199)', position: 0.6 },
            { color: 'rgb(239,138,98)', position: 0.8 },
            { color: 'rgb(178,24,43,1.0)', position: 1 },
          ],
        },
        zoom: {
          position: 'bottomright',
        },
        legend: {
          position: 'bottomleft',
        },
      },]
    });
  });

🏞 Expected result

希望左下角是有图例的

结果

是暂不支持吗？我看文档里多图表还是unstable，有啥解决方案建议？还是说配置不对？