merge method

Implementation

DropDownElementStyle merge(DropDownElementStyle mergeWith) {
  return DropDownElementStyle(
    optionTextStyle: optionTextStyle ?? mergeWith.optionTextStyle,
    labelStyle: labelStyle ?? mergeWith.labelStyle,
    hintTextStyle: hintTextStyle ?? mergeWith.hintTextStyle,
    width: width ?? mergeWith.width,
    height: height ?? mergeWith.height,
    background: background ?? mergeWith.background,
    border: border ?? mergeWith.border,
    borderRadius: borderRadius ?? mergeWith.borderRadius,
    gradient: gradient ?? mergeWith.gradient,
  );
}