title: Flutter DropDownButton using FutureBuilder value is not updating after selecting values from DropdownItems
body: <p>I have been trying to code this app using Flutter and I want to make a Dropdown that displays the values received from a JSON response via provider. The response is successful from the service and correctly fetches the data. Dropdown is wrapped in a FutureBuilder, the information can be displayed without problems in the Dropdown, the problem is generated when I want to select an element, it is not updated, for this reason it is not reflected.</p>
  <p>My code:</p>
  <pre><code> List&lt;Datum&gt; listDatumEnterprise;
  Datum _selectEnterprise;
  
  return FutureBuilder(
      future: getInformationAdministrative.enterpriseDataGet(),
      builder: (BuildContext context, AsyncSnapshot&lt;List&lt;Datum&gt;&gt; snapshot) {
        if (snapshot.hasData) {
          listDatumEnterprise = snapshot.data;
          return CustomDropDown&lt;Datum&gt;(
            title: 'Selecciona empresa',
            value: _selectEnterprise,
            onChanged: (Datum datum) {
              setState(() {
                _selectEnterprise = datum;
                print(_selectEnterprise.id);
              });
            },
            dropdownMenuItemList: listDatumEnterprise?.map((Datum item) {
                  return new DropdownMenuItem&lt;Datum&gt;(
                    child: Text(item.alias),
                    value: item,
                  );
                })?.toList() ??
                [],
          );
        } else {
          return CircularProgressIndicator();
        }
  </code></pre>
  <p><a href="https://i.stack.imgur.com/IPvQD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IPvQD.png" alt="Data obtained from snapshot " /></a></p>