Implementation
set apply(NikuCheckbox? v) {
if (v == null) return;
onChanged = v.onChanged ?? onChanged;
mouseCursor = v.mouseCursor ?? mouseCursor;
activeColor = v.activeColor ?? activeColor;
fillColorState = v.fillColorState ?? fillColorState;
checkColor = v.checkColor ?? checkColor;
tristate = v.tristate ?? tristate;
materialTapTargetSize = v.materialTapTargetSize ?? materialTapTargetSize;
visualDensity = v.visualDensity ?? visualDensity;
focusColor = v.focusColor ?? focusColor;
hoverColor = v.hoverColor ?? hoverColor;
overlayColorState = v.overlayColorState ?? overlayColorState;
splashRadius = v.splashRadius ?? splashRadius;
focusNode = v.focusNode ?? focusNode;
autofocus = v.autofocus ?? autofocus;
shape = v.shape ?? shape;
side = v.side ?? side;
$parent..$merge(v.$parent);
}