closeIconColor property
final
(optional) An optional color for the close icon, if showCloseIcon is true.
If this property is null, then SnackBarThemeData.closeIconColor of ThemeData.snackBarTheme is used. If that is null, then the default is inverse surface.
If closeIconColor is a MaterialStateColor, then the icon color will be resolved against the set of MaterialStates that the action text is in, thus allowing for different colors for states such as pressed, hovered and others.
Implementation
final Color? closeIconColor;