@Nullable
  private static Color mixBackground(@Nullable Color color, @Nullable Color defaultBackground, double alpha) {
    if (color == null || defaultBackground == null || alpha < 0) {
      return null;
    }
    return ColorUtil.mix(defaultBackground, color, alpha);
  }
@Nullable
  private static Color mixBackground(@Nullable Color color, @Nullable Color defaultBackground, double alpha)