The (optional) content of the dialog is displayed in the center of the dialog in a lighter font.
Typically this is a SingleChildScrollView that contains the dialog's message. As noted in the AlertDialog documentation, it's important to use a SingleChildScrollView if there's any risk that the content will not fit, as the contents will otherwise overflow the dialog.
The content must support reporting its intrinsic dimensions. In particular, ListView, GridView, and CustomScrollView cannot be used here unless they are first wrapped in a widget that itself can report intrinsic dimensions, such as a SizedBox.
final Widget? content;