merge method
Implementation
DividerThemeData merge(DividerThemeData? style) {
if (style == null) return this;
return DividerThemeData(
decoration: style.decoration ?? decoration,
thickness: style.thickness ?? thickness,
horizontalMargin: style.horizontalMargin ?? horizontalMargin,
verticalMargin: style.verticalMargin ?? verticalMargin,
);
}