Flutter nulo onpressado

  body: const Center(
          child: FlatButton(
            color: Colors.blue,
            textColor: Colors.white,
            highlightColor: Colors.green,
            splashColor: Colors.red,
            padding: EdgeInsets.symmetric(vertical: 20.0, horizontal: 20.0),
            onPressed: null,
            child: Text(
              "Flat Button",
              style: TextStyle(fontSize: 34.0),
            ),
          ),
        ),
Tender Tern