code: function mappingToTable(mapping) {
    const mp = mapping.hasOwnProperty('field') ? singleToMulti(mapping) : mapping;
    const keyField = {key: mp.key, format: 'text'};
    const data = {
      fields: [keyField].concat(mp.fields),
      records: Object.entries(mp.mapping).map(entry => {
        const rcd = {};
        rcd[mp.key] = entry[0];
        mp.fields.forEach((f, i) => {
          rcd[f.key] = entry[1][i];
        });
        return rcd;
      })
    };
    return data;
  }
docs: Convert field mapping to table
  @param {object} mapping - field mapping
  @return {object} table object