NextAlert constructor
      const
      NextAlert({ 
    
- Key? key,
- bool visible = true,
- BorderRadiusGeometry borderRadius = const BorderRadius.all(Radius.circular(4)),
- Widget? trailing,
- Widget? heading,
- void onClosedIconPressed()?,
- NextVariant variant = NextVariant.primary,
- TextStyle? textStyle,
- double verticalHeadingSpace = 10.0,
- TextStyle? headingTextStyle,
- NextAlertColorUtils? customConfigs,
- EdgeInsetsGeometry? margin,
- EdgeInsetsGeometry? padding,
- Widget? child,
- Widget transitionBuilder()?,
Construct NextAlert
Implementation
const NextAlert(
    {Key? key,
    this.visible = true,
    this.borderRadius = const BorderRadius.all(Radius.circular(4)),
    this.trailing,
    this.heading,
    this.onClosedIconPressed,
    this.variant = NextVariant.primary,
    this.textStyle,
    this.verticalHeadingSpace = 10.0,
    this.headingTextStyle,
    this.customConfigs,
    this.margin,
    this.padding,
    this.child,
    this.transitionBuilder})
    : super(key: key);