title: Flutter List<Dynamic> should be List<DataRow>
body: <p>I'm trying to use flutter's DataTable widget but I keep getting this error, I want to create a method to generate the data for the table.</p>
  
  <pre><code>var dataList = [
      DataSectionCollection(
        category: 'Category',
        date: 'January 01, 2019',
        item: [
          DataSectionItem(
              symbol: "ICMS", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "ICMS", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "ICMS", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "ICMS", amount: " 474.858.228.17", percentage: 3.55),
        ],
      ),
      DataSectionCollection(
        category: 'Category',
        date: 'January 01, 2019',
        item: [
          DataSectionItem(
              symbol: "AAAA", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "AAA", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "AAA", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "AAA", amount: " 474.858.228.17", percentage: 3.55),
        ],
      ),
      DataSectionCollection(
        category: 'Category',
        date: 'January 01, 2019',
        item: [
          DataSectionItem(
              symbol: "BBBB", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "BBBB", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "BBBB", amount: " 474.858.228.17", percentage: 3.55),
          DataSectionItem(
              symbol: "BBBB", amount: " 474.858.228.17", percentage: 3.55),
        ],
      ),
    ];
  
    _getData01(List listOfData) {
      return DataTable(
        columns: listOfData
            .map(
              (column) =&gt; DataColumn(
                label: Container(),
              ),
            )
            .toList(),
        rows: listOfData
            .map((stat) =&gt; stat.item.map((row) =&gt; DataRow(cells: [
                  DataCell(
                    Text(row.symbol),
                  ),
                  DataCell(
                    Text(row.amount),
                  ),
                  DataCell(
                    Text("${row.symbol}"),
                  ),
                ])))
            .toList(),
      );
    }
  </code></pre>
  
  <p>I'm not entirely sure what i'm doing wrong. Can someone help please? The first bit where i map over the list to create the columns work fine by the second didn't.</p>