Dart APIunself_styleCustomColorsgoldContainer goldContainer property Null safety Color? goldContainer final Implementation final Color? goldContainer; unself_style unself_style CustomColors goldContainer property CustomColors class Constructors CustomColors Properties gold goldContainer hashCode mauve mauveContainer onGold onGoldContainer onMauve onMauveContainer onVanilla onVanillaContainer runtimeType sourceGold sourceMauve sourceVanilla type vanilla vanillaContainer Methods copyWith harmonized lerp noSuchMethod toString Operators operator ==