merge method
Implementation
BoxDecoration merge(BoxDecoration? other) {
if (other == null) return this;
return copyWith(
color: other.color,
image: other.image,
border: other.border,
borderRadius: other.borderRadius,
boxShadow: other.boxShadow,
gradient: other.gradient,
backgroundBlendMode: other.backgroundBlendMode,
shape: other.shape,
);
}