myColor

Theme

of

context

accentColor

Code after migration:

Color

myColor

Theme

of

context

colorScheme

secondary

accentColorBrightness

The static ThemeData.estimateBrightnessForColor() method can be used
to compute the brightness of any color.

accentTextTheme

This was white TextStyles for dark themes, black
TextStyles for light themes. In most cases textTheme can be used
instead. A common idiom was to refer to one TextStyle from
accentTextTheme, since the text style’s color was guaranteed to contrast
well with the accent color (now ColorScheme.secondaryColor).  To get
the same result now, specify the text style’s color as
ColorScheme.onSecondary: