How to add more metrics on the country_map in Apache-superset?

I am using country_map in apache-superset for visualization purposes. When zooming in on a polygon, information from the columns appears inside of the polygon, like so:

There is only one available metric option to display:

Code for the metric update is found on this path:

superset/assets/src/visualizations/CountryMap/CountryMap.js

Code:

const updateMetrics = function (region) {
  if (region.length > 0) {     
    resultText.text(format(region[0].metric));
  }
};

The metrics are defined in controls.jsx:

/superset/static/assets/src/explore/controls.jsx

const metrics = {
  type: 'MetricsControl',
  multi: true,
  label: t('Metrics'),
  validators: [v.nonEmpty],
  default: (c) => {
    const metric = mainMetric(c.savedMetrics);
    return metric ? [metric] : null;
  },
  mapStateToProps: (state) => {
    const datasource = state.datasource;
    return {
      columns: datasource ? datasource.columns : [],
      savedMetrics: datasource ? datasource.metrics : [],
      datasourceType: datasource && datasource.type,
    };
  },
  description: t('One or many metrics to display'),
};
const metric = {
  ...metrics,
  multi: false,
  label: t('Metric'),
  default: props => mainMetric(props.savedMetrics),
};

Country map is using metric, which doesn't allow multiple metrics to be selected, Code found here:

superset/assets/src/explore/controlPanels/CountryMap.js

  controlPanelSections: [
    {
      label: t('Query'),
      expanded: true,
      controlSetRows: [
        ['entity'],
        ['metric'],
        ['adhoc_filters'],
      ],
    },
    {
      label: t('Options'),
      expanded: true,
      controlSetRows: [
        ['select_country', 'number_format'],
        ['linear_color_scheme'],
      ],
    },
  ],

Changing the code in CountryMap.js and viz.py from metric to metrics results in the following error:

Traceback (most recent call last):
  File "/Documents/superset/superset/superset/viz.py", line 410, in get_df_payload
    df = self.get_df(query_obj)
  File "/Documents/superset/superset/superset/viz.py", line 213, in get_df
    self.results = self.datasource.query(query_obj)
  File "/Documents/superset/superset/superset/connectors/sqla/models.py", line 797, in query
    sql = self.get_query_str(query_obj)
  File "/Documents/superset/superset/superset/connectors/sqla/models.py", line 471, in get_query_str
    qry = self.get_sqla_query(**query_obj)
  File "/Documents/superset/superset/superset/connectors/sqla/models.py", line 585, in get_sqla_query
    elif m in metrics_dict:
TypeError: unhashable type: 'list'

How can I add more metrics to display inside the polygon?

from How to add more metrics on the country_map in Apache-superset?