>>> (indent 4)
    children.add(new DrawerHeader(children: [
        new Flex([avatar, username],
            justifyContent: FlexJustifyContent.center,
            direction: FlexDirection.vertical)]));
<<<
    children.add(
      new DrawerHeader(
        children: [
          new Flex(
            [avatar, username],
            justifyContent: FlexJustifyContent.center,
            direction: FlexDirection.vertical,
          ),
        ],
      ),
    );