Flutter extract widget requires a return widget

I am getting a lot of widgets groups in the tree and wanted to start extracting them to their own widget.

I tried with Ctrl-Alt-W, this command does nothing and shows no error when there is a problem.

If you go to the top menu and click on refactor, extract, extract to widget the following error occurs:

Can only extract a widget expression or a method returning widget.

This is an example of the code I am trying to extract:

                     Expanded(
                          child: Container(
                            child: Padding(
                              padding: const EdgeInsets.only(
                                  left: 8.0,
                                  right: 8.0,
                                  top: 8.0,
                                  bottom: 4.0),
                              child: new TextField(
                                decoration: new InputDecoration(
                                    border: new OutlineInputBorder(
                                      borderRadius: const BorderRadius.all(
                                        const Radius.circular(10.0),
                                      ),
                                    ),
                                    filled: true,
                                    hintStyle: new TextStyle(
                                        color: Colors.grey[800]),
                                    hintText: "Supervisor",
                                    fillColor: Colors.white70),
                              ),
                            ),
                          ),
                        ),

How would I modify this code in the widget tree to have a return so that it can be easily extracted.

Thanks